[python3] Use vcpkg expat port instead of vendored code.

This fixes an observed build failure on x86-windows when the vcpkg expat
port is installed before the python3 port is built.

ports/python3/0001-static-library.patch

@@ -1,7 +1,7 @@
 From 79ec7506399bc3846bb0631827e3880f5468e507 Mon Sep 17 00:00:00 2001
 From: Adam Johnson <[email protected]>
 Date: Sun, 13 Sep 2020 21:33:33 -0400
-Subject: [PATCH 1/7] Static library
+Subject: [PATCH 1/8] Static library
 
 
 diff --git a/PC/pyconfig.h b/PC/pyconfig.h

ports/python3/0002-always-use-vcpkg-zlib.patch

@@ -1,7 +1,7 @@
 From 175b0e8c0d5d4ba1da3d9313a0208c8b814792f0 Mon Sep 17 00:00:00 2001
 From: Adam Johnson <[email protected]>
 Date: Wed, 9 Sep 2020 15:20:36 -0400
-Subject: [PATCH 2/7] Always use vcpkg zlib
+Subject: [PATCH 2/8] Always use vcpkg zlib
 
 Building without zlib is not a supported configuration, per the warning
 messages.

ports/python3/0003-remove-external-dependencies.patch

@@ -1,7 +1,7 @@
 From d69746248f01a3eca82f441e789279e9d0acaf08 Mon Sep 17 00:00:00 2001
 From: Adam Johnson <[email protected]>
 Date: Wed, 9 Sep 2020 15:24:38 -0400
-Subject: [PATCH 3/7] Remove external dependencies
+Subject: [PATCH 3/8] Remove external dependencies
 
 The externally fetched libraries may cause linker errors resulting from
 duplicate symbols in downstream projects.

ports/python3/0004-don-t-copy-vcruntime.patch

@@ -1,7 +1,7 @@
 From 04b72da23e00abb1a5ff02aa5b0cb54576d45051 Mon Sep 17 00:00:00 2001
 From: Adam Johnson <[email protected]>
 Date: Wed, 9 Sep 2020 16:12:49 -0400
-Subject: [PATCH 4/7] Don't copy vcruntime
+Subject: [PATCH 4/8] Don't copy vcruntime
 
 VCRUNTIME140.dll should not be redistributed, ever.
 

ports/python3/0005-only-build-required-projects.patch

@@ -1,7 +1,7 @@
 From dfb70394a19e657f2700fa31b784b0ea538b2a70 Mon Sep 17 00:00:00 2001
 From: Adam Johnson <[email protected]>
 Date: Wed, 9 Sep 2020 20:15:58 -0400
-Subject: [PATCH 5/7] Only build required projects
+Subject: [PATCH 5/8] Only build required projects
 
 Strips out tests and unsupported externals (eg tkinter).
 

ports/python3/0006-fix-duplicate-symbols.patch

@@ -1,7 +1,7 @@
 From 4d698284921b48b963caa26a352ef414f36f36d4 Mon Sep 17 00:00:00 2001
 From: Adam Johnson <[email protected]>
 Date: Fri, 11 Sep 2020 12:35:36 -0400
-Subject: [PATCH 6/7] fix duplicate symbols
+Subject: [PATCH 6/8] fix duplicate symbols
 
 
 diff --git a/Modules/_winapi.c b/Modules/_winapi.c

ports/python3/0007-disable-static-PYD-loading.patch

@@ -1,7 +1,7 @@
 From eaf5d60b5de65f8d1f8f32535cd2e42da3115f00 Mon Sep 17 00:00:00 2001
 From: Adam Johnson <[email protected]>
 Date: Sun, 13 Sep 2020 19:38:30 -0400
-Subject: [PATCH 7/7] Disable static PYD loading
+Subject: [PATCH 7/8] Disable static PYD loading
 
 Loading shared *.pyd extensions with a static python on Windows crashes
 the interpreter. Don't do that.

ports/python3/0008-always-use-vcpkg-expat.patch

@@ -0,0 +1,37 @@
+From 0fb7abf948c0c6157a49126c90ef661ef59cd11f Mon Sep 17 00:00:00 2001
+From: Adam Johnson <[email protected]>
+Date: Wed, 16 Sep 2020 16:48:38 -0400
+Subject: [PATCH 8/8] Always use vcpkg expat
+
+The vendored expat library causes errors when building the port on
+x86-windows after the expat port has been built.
+
+diff --git a/PCbuild/pyexpat.vcxproj b/PCbuild/pyexpat.vcxproj
+index b2d9f5d57d..4efb826a05 100644
+--- a/PCbuild/pyexpat.vcxproj
++++ b/PCbuild/pyexpat.vcxproj
+@@ -89,17 +89,19 @@
+   </ImportGroup>
+   <PropertyGroup Label="UserMacros" />
+   <ItemDefinitionGroup>
+-    <ClCompile>
++    <ClCompile Condition="false">
+       <AdditionalIncludeDirectories>$(PySourcePath)Modules\expat;%(AdditionalIncludeDirectories)</AdditionalIncludeDirectories>
+       <PreprocessorDefinitions>_CRT_SECURE_NO_WARNINGS;PYEXPAT_EXPORTS;HAVE_EXPAT_H;XML_STATIC;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+     </ClCompile>
+   </ItemDefinitionGroup>
+-  <ItemGroup>
++  <ItemGroup Condition="false">
+     <ClInclude Include="..\Modules\expat\xmlrole.h" />
+     <ClInclude Include="..\Modules\expat\xmltok.h" />
+   </ItemGroup>
+   <ItemGroup>
+     <ClCompile Include="..\Modules\pyexpat.c" />
++  </ItemGroup>
++  <ItemGroup Condition="false">
+     <ClCompile Include="..\Modules\expat\xmlparse.c" />
+     <ClCompile Include="..\Modules\expat\xmlrole.c" />
+     <ClCompile Include="..\Modules\expat\xmltok.c" />
+-- 
+2.28.0.windows.1
+

ports/python3/portfile.cmake

@@ -16,6 +16,7 @@ set(PATCHES
     0005-only-build-required-projects.patch
     0006-fix-duplicate-symbols.patch
     0007-disable-static-PYD-loading.patch
+    0008-always-use-vcpkg-expat.patch
 )
 
 vcpkg_from_github(
@@ -40,6 +41,8 @@ if(VCPKG_TARGET_IS_WINDOWS OR VCPKG_TARGET_IS_UWP)
         find_library(BZ2_DEBUG NAMES bz2 bz2d PATHS "${CURRENT_INSTALLED_DIR}/debug/lib" NO_DEFAULT_PATH)
         find_library(CRYPTO_RELEASE NAMES libcrypto PATHS "${CURRENT_INSTALLED_DIR}/lib" NO_DEFAULT_PATH)
         find_library(CRYPTO_DEBUG NAMES libcrypto PATHS "${CURRENT_INSTALLED_DIR}/debug/lib" NO_DEFAULT_PATH)
+        find_library(EXPAT_RELEASE NAMES libexpat PATHS "${CURRENT_INSTALLED_DIR}/lib" NO_DEFAULT_PATH)
+        find_library(EXPAT_DEBUG NAMES libexpat libexpatd PATHS "${CURRENT_INSTALLED_DIR}/debug/lib" NO_DEFAULT_PATH)
         find_library(FFI_RELEASE NAMES libffi PATHS "${CURRENT_INSTALLED_DIR}/lib" NO_DEFAULT_PATH)
         find_library(FFI_DEBUG NAMES libffi PATHS "${CURRENT_INSTALLED_DIR}/debug/lib" NO_DEFAULT_PATH)
         find_library(LZMA_RELEASE NAMES lzma PATHS "${CURRENT_INSTALLED_DIR}/lib" NO_DEFAULT_PATH)
@@ -140,7 +143,12 @@ if(VCPKG_TARGET_IS_WINDOWS OR VCPKG_TARGET_IS_UWP)
 
     vcpkg_clean_msbuild()
 else()
-    set(OPTIONS "--with-openssl=${CURRENT_INSTALLED_DIR}" "--with-ensurepip" [[--with-suffix=""]])
+    set(OPTIONS
+        "--with-openssl=${CURRENT_INSTALLED_DIR}"
+        "--with-ensurepip"
+        [[--with-suffix=""]]
+        "--with-system-expat"
+    )
     if(VCPKG_TARGET_IS_OSX)
         list(APPEND OPTIONS "LIBS=-liconv -lintl")
     endif()

ports/python3/python_vcpkg.props.in

@@ -4,6 +4,7 @@
     <CLCompile>
       <!-- Use vcpkg ports instead of vendored externals -->
       <PreprocessorDefinitions>_Py_HAVE_ZLIB;%(PreprocessorDefinitions)</PreprocessorDefinitions>
+      <PreprocessorDefinitions Condition="${VCPKG_LIBRARY_LINKAGE} == 'static'">XML_STATIC;%(PreprocessorDefinitions)</PreprocessorDefinitions>
       <AdditionalIncludeDirectories>
         ${CURRENT_INSTALLED_DIR}/include;%(AdditionalIncludeDirectories)
       </AdditionalIncludeDirectories>
@@ -24,10 +25,10 @@
 
       <!-- Extension modules -->
       <AdditionalDependencies Condition="'$(Configuration)|$(IncludeExtensions)' == 'Release|true'">
-        ${BZ2_RELEASE};${FFI_RELEASE};${LZMA_RELEASE};${SQLITE_RELEASE};%(AdditionalDependencies)
+        ${BZ2_RELEASE};${EXPAT_RELEASE};${FFI_RELEASE};${LZMA_RELEASE};${SQLITE_RELEASE};%(AdditionalDependencies)
       </AdditionalDependencies>
       <AdditionalDependencies Condition="'$(Configuration)|$(IncludeExtensions)' == 'Debug|true'">
-        ${BZ2_DEBUG};${FFI_DEBUG};${LZMA_DEBUG};${SQLITE_DEBUG};%(AdditionalDependencies)
+        ${BZ2_DEBUG};${EXPAT_DEBUG};${FFI_DEBUG};${LZMA_DEBUG};${SQLITE_DEBUG};%(AdditionalDependencies)
       </AdditionalDependencies>
     </Link>
   </ItemDefinitionGroup>

ports/python3/vcpkg.json

@@ -9,6 +9,7 @@
       "name": "bzip2",
       "platform": "!(windows & static)"
     },
+    "expat",
     {
       "name": "gettext",
       "platform": "!(windows | uwp)"