add libusb-specific hid_libusb_wrap_sys_device

Rationale: on Android one must use UsbManager, to access any
USB device. As a result, libraries like libusb can only use file descriptors
that are provided by UsbManager.
libusb has an API to use such file descriptors: hid_libusb_wrap_sys_device.
Having hid_libusb_wrap_sys_device currently is the only way to make hidapi
work on Android without root access and without custom Android builds.

Relevant info: https://github.com/libusb/libusb/pull/830/files

.github/workflows/builds.yml

@@ -47,7 +47,10 @@ jobs:
     - name: Check artifacts
       uses: andstor/file-existence-action@v1
       with:
-        files: "install/shared/lib/libhidapi.dylib, install/shared/include/hidapi/hidapi.h, install/framework/lib/hidapi.framework/hidapi, install/framework/lib/hidapi.framework/Headers/hidapi.h"
+        files: "install/shared/lib/libhidapi.dylib, \
+                install/shared/include/hidapi/hidapi.h, \
+                install/framework/lib/hidapi.framework/hidapi, \
+                install/framework/lib/hidapi.framework/Headers/hidapi.h"
         allow_failure: true
 
   ubuntu-cmake:
@@ -76,7 +79,14 @@ jobs:
     - name: Check artifacts
       uses: andstor/file-existence-action@v1
       with:
-        files: "install/shared/lib/libhidapi-libusb.so, install/shared/lib/libhidapi-hidraw.so, install/shared/include/hidapi/hidapi.h, install/static/lib/libhidapi-libusb.a, install/static/lib/libhidapi-hidraw.a, install/static/include/hidapi/hidapi.h"
+        files: "install/shared/lib/libhidapi-libusb.so, \
+                install/shared/lib/libhidapi-hidraw.so, \
+                install/shared/include/hidapi/hidapi.h, \
+                install/shared/include/hidapi/hidapi_libusb.h, \
+                install/static/lib/libhidapi-libusb.a, \
+                install/static/lib/libhidapi-hidraw.a, \
+                install/static/include/hidapi/hidapi.h, \
+                install/static/include/hidapi/hidapi_libusb.h"
         allow_failure: true
 
   windows-cmake-msvc:

libusb/CMakeLists.txt

@@ -3,6 +3,7 @@ cmake_minimum_required(VERSION 3.6.3 FATAL_ERROR)
 add_library(hidapi_libusb
     ${HIDAPI_PUBLIC_HEADERS}
     hid.c
+    hidapi_libusb.h
 )
 target_link_libraries(hidapi_libusb PUBLIC hidapi_include)
 
@@ -23,7 +24,7 @@ set_target_properties(hidapi_libusb
         OUTPUT_NAME "hidapi-libusb"
         VERSION ${PROJECT_VERSION}
         SOVERSION ${PROJECT_VERSION_MAJOR}
-        PUBLIC_HEADER "${HIDAPI_PUBLIC_HEADERS}"
+        PUBLIC_HEADER "${HIDAPI_PUBLIC_HEADERS};hidapi_libusb.h"
 )
 
 # compatibility with find_package()

libusb/Makefile.am

@@ -29,6 +29,6 @@ libhidapi_la_LIBADD = $(LIBS_LIBUSB)
 endif
 
 hdrdir = $(includedir)/hidapi
-hdr_HEADERS = $(top_srcdir)/hidapi/hidapi.h
+hdr_HEADERS = $(top_srcdir)/hidapi/hidapi.h hidapi_libusb.h
 
 EXTRA_DIST = Makefile-manual