Fix python2's build and clean up the recipe

Actions taken:

  - I found that a lot of basic python modules get not compiled. Here we solve that issue by creating a patch (fix-missing-extensions.patch) adapted from the one applied to the python3's master branch. This new patch replaces the "fix-modules-initialization" (which worked but not compiled the necessary modules into .so files). Now all the needed modules should be present.

    * Note: **Should be mentioned that the ctypes module builds without a problem for python2 (no need to link with custom libffi as we do in python 3 in pr kivy#1465)**

  - I reviewed all the patches to move all the unneeded into a sub folder (maybe we can need some of them...)

    * Note: all the patches where made to be applied into the old python2's build system, and only those which allows the native build to succeed and the ones which fix python initialization should be needed with the new build system

  - Rename patches to be clear and to remove some upper cases and versions (we will not have many more future versions for python2 and I think that removing this versions make the code more readable)

pythonforandroid/recipes/python2/__init__.py

@@ -1,6 +1,4 @@
 from pythonforandroid.python import GuestPythonRecipe
-from pythonforandroid.patching import (
-    is_darwin, is_api_gt, check_all, is_api_lt, is_ndk)
 
 
 class Python2Recipe(GuestPythonRecipe):
@@ -24,32 +22,12 @@ class Python2Recipe(GuestPythonRecipe):
 
     patches = [
                # new 2.7.15 patches
-               # ('patches/Python-2.7.15-fix-api-minor-than-21.patch',
-               #  is_api_lt(21)), # todo: this should be tested
-               'patches/fix-modules-initialization.patch',
-               'patches/Python_{version}-ctypes-libffi-fix-configure.patch',
-               'patches/ffi-config.sub-{version}.patch',
-               'patches/fix-locale-{version}.patch',
-               'patches/modules-locales-{version}.patch',
-               'patches/fix-platform-{version}.patch',
-               # migrated patches from 2.7.2
-               'patches/fix-gethostbyaddr.patch',
-               'patches/fix-filesystemdefaultencoding.patch',
-               'patches/fix-termios.patch',
-               'patches/custom-loader.patch',
-               'patches/fix-remove-corefoundation.patch',
-               'patches/fix-dynamic-lookup.patch',
-               'patches/fix-dlfcn.patch',
-               'patches/ctypes-find-library.patch',
-               'patches/Python-{version}-ctypes-disable-wchar.patch',
-               'patches/disable-modules.patch',
-               'patches/verbose-compilation.patch',
-               # migrated special patches from 2.7.2
-               ('patches/fix-configure-darwin.patch', is_darwin),
-               ('patches/fix-distutils-darwin.patch', is_darwin),
-               ('patches/fix-ftime-removal.patch', is_api_gt(19)),
-               ('patches/disable-openpty.patch', check_all(
-                   is_api_lt(21), is_ndk('crystax')))
+               # ('patches/fix-api-minor-than-21.patch',
+               #  is_api_lt(21)), # Todo: this should be tested
+               'patches/fix-missing-extensions.patch',
+               'patches/fix-filesystem-default-encoding.patch',
+               'patches/fix-locale.patch',
+               'patches/fix-init-site.patch',
                ]
 
     configure_args = ('--host={android_host}',
@@ -62,10 +40,7 @@ class Python2Recipe(GuestPythonRecipe):
                       'ac_cv_file__dev_ptc=no',
                       '--without-ensurepip',
                       'ac_cv_little_endian_double=yes',
-
-                      # why python3 works without it?
                       'ac_cv_header_langinfo_h=no',
-
                       '--prefix={prefix}',
                       '--exec-prefix={exec_prefix}')
 

pythonforandroid/recipes/python2/patches/fix-init-site.patch

@@ -0,0 +1,17 @@
+--- Python-2.7.2.orig/Python/pythonrun.c	2010-10-29 05:45:34.000000000 +0200
++++ Python-2.7.2/Python/pythonrun.c	2011-04-20 17:52:12.000000000 +0200
+@@ -254,9 +254,13 @@
+     _PyGILState_Init(interp, tstate);
+ #endif /* WITH_THREAD */
+
++    /* For PGS4A, we don't want to call initsite, as we won't have the
++       library path set up until start.pyx finishes running. */
++#if 0
+     if (!Py_NoSiteFlag)
+         initsite(); /* Module site */
+-
++#endif 
++    
+     if ((p = Py_GETENV("PYTHONIOENCODING")) && *p != '\0') {
+         p = icodeset = codeset = strdup(p);
+         free_codeset = 1;

pythonforandroid/recipes/python2/patches/fix-missing-extensions.patch

@@ -0,0 +1,120 @@
+diff -Naurp Python-2.7.15/Modules/Setup.dist.orig Python-2.7.15/Modules/Setup.dist
+--- Python-2.7.15/Modules/Setup.dist.orig	2018-04-30 00:47:33.000000000 +0200
++++ Python-2.7.15/Modules/Setup.dist	2018-11-17 20:40:20.153518694 +0100
+@@ -464,7 +464,7 @@
+ # Andrew Kuchling's zlib module.
+ # This require zlib 1.1.3 (or later).
+ # See http://www.gzip.org/zlib/
+-#zlib zlibmodule.c -I$(prefix)/include -L$(exec_prefix)/lib -lz
++zlib zlibmodule.c -I$(prefix)/include -L$(exec_prefix)/lib -lz
+
+ # Interface to the Expat XML parser
+ #
+diff -Naurp Python-2.7.15.orig/Makefile.pre.in Python-2.7.15/Makefile.pre.in
+--- Python-2.7.15.orig/Makefile.pre.in	2018-04-30 00:47:33.000000000 +0200
++++ Python-2.7.15/Makefile.pre.in	2018-11-18 00:43:58.777379280 +0100
+@@ -20,6 +20,7 @@
+
+ # === Variables set by makesetup ===
+
++MODNAMES=       _MODNAMES_
+ MODOBJS=        _MODOBJS_
+ MODLIBS=        _MODLIBS_
+
+diff -Naurp Python-2.7.15.orig/Modules/_ctypes/libffi/src/arm/sysv.S Python-2.7.15/Modules/_ctypes/libffi/src/arm/sysv.S
+--- Python-2.7.15.orig/Modules/_ctypes/libffi/src/arm/sysv.S	2018-04-30 00:47:33.000000000 +0200
++++ Python-2.7.15/Modules/_ctypes/libffi/src/arm/sysv.S	2018-11-17 22:28:50.925456603 +0100
+@@ -396,7 +396,7 @@ LSYM(Lbase_args):
+ 	beq	LSYM(Lepilogue_vfp)
+
+ 	cmp	r3, #FFI_TYPE_SINT64
+-	stmeqia	r2, {r0, r1}
++	stmiaeq	r2, {r0, r1}
+ 	beq	LSYM(Lepilogue_vfp)
+
+ 	cmp	r3, #FFI_TYPE_FLOAT
+diff -Naurp Python-2.7.15.orig/Modules/makesetup Python-2.7.15/Modules/makesetup
+--- Python-2.7.15.orig/Modules/makesetup	2018-04-30 00:47:33.000000000 +0200
++++ Python-2.7.15/Modules/makesetup	2018-11-18 00:43:10.289379743 +0100
+@@ -110,6 +110,7 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
+ # Rules appended by makedepend
+ " >$rulesf
+ 	DEFS=
++	NAMES=
+ 	MODS=
+ 	SHAREDMODS=
+ 	OBJS=
+@@ -181,7 +182,7 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
+ 			*.*)		echo 1>&2 "bad word $arg in $line"
+ 					exit 1;;
+ 			-u)		skip=libs; libs="$libs -u";;
+-			[a-zA-Z_]*)	mods="$mods $arg";;
++			[a-zA-Z_]*)	NAMES="$NAMES $arg"; mods="$mods $arg";;
+ 			*)		echo 1>&2 "bad word $arg in $line"
+ 					exit 1;;
+ 			esac
+@@ -284,6 +285,7 @@ sed -e 's/[ 	]*#.*//' -e '/^[ 	]*$/d' |
+ 		echo "1i\\" >$sedf
+ 		str="# Generated automatically from $makepre by makesetup."
+ 		echo "$str" >>$sedf
++		echo "s%_MODNAMES_%$NAMES%" >>$sedf
+ 		echo "s%_MODOBJS_%$OBJS%" >>$sedf
+ 		echo "s%_MODLIBS_%$LIBS%" >>$sedf
+ 		echo "/Definitions added by makesetup/a$NL$NL$DEFS" >>$sedf
+diff -Naurp Python-2.7.15.orig/setup.py Python-2.7.15/setup.py
+--- Python-2.7.15.orig/setup.py	2018-04-30 00:47:33.000000000 +0200
++++ Python-2.7.15/setup.py	2018-11-18 00:40:50.021381080 +0100
+@@ -217,7 +217,11 @@ class PyBuildExt(build_ext):
+         # Python header files
+         headers = [sysconfig.get_config_h_filename()]
+         headers += glob(os.path.join(sysconfig.get_path('include'), "*.h"))
+-        for ext in self.extensions[:]:
++        # The sysconfig variable built by makesetup, listing the already
++        # built modules as configured by the Setup files.
++        modnames = sysconfig.get_config_var('MODNAMES').split()
++        removed_modules = []
++        for ext in self.extensions:
+             ext.sources = [ find_module_file(filename, moddirlist)
+                             for filename in ext.sources ]
+             if ext.depends is not None:
+@@ -231,10 +235,10 @@ class PyBuildExt(build_ext):
+             # platform specific include directories
+             ext.include_dirs.extend(incdirlist)
+
+-            # If a module has already been built statically,
+-            # don't build it here
+-            if ext.name in sys.builtin_module_names:
+-                self.extensions.remove(ext)
++            # If a module has already been built by the Makefile,
++            # don't build it here.
++            if ext.name in modnames:
++                removed_modules.append(ext)
+
+         # Parse Modules/Setup and Modules/Setup.local to figure out which
+         # modules are turned on in the file.
+@@ -249,8 +253,9 @@ class PyBuildExt(build_ext):
+             input.close()
+
+         for ext in self.extensions[:]:
+-            if ext.name in remove_modules:
+-                self.extensions.remove(ext)
++            if removed_modules:
++                self.extensions = [x for x in self.extensions if x not in
++                                   removed_modules]
+
+         # When you run "make CC=altcc" or something similar, you really want
+         # those environment variables passed into the setup.py phase.  Here's
+@@ -290,6 +295,13 @@ class PyBuildExt(build_ext):
+                    " detect_modules() for the module's name.")
+             print
+
++        if removed_modules:
++            print("The following modules found by detect_modules() in"
++                  " setup.py, have been")
++            print("built by the Makefile instead, as configured by the"
++                  " Setup files:")
++            print_three_column([ext.name for ext in removed_modules])
++
+         if self.failed:
+             failed = self.failed[:]
+             print