[issue27453] Fix cross-compilation with Android NDK and Clang

[Xavier de Gaye]

Xavier de Gaye added the comment:

With configure run as './configure CC="$(CC)" ...' and when CC is set to:
CC = clang --sysroot=$(SYSROOT) -target $(TARGET) -gcc-toolchain $(GCC_TOOLCHAIN)

and building for armv7 on android-21, then configure runs $CPP as:

checking for CPP... clang --sysroot=/opt/android-ndk/platforms/android-21/arch-arm -target armv7-none-linux-androideabi -gcc-toolchain /opt/android-ndk/toolchains/arm-linux-androideabi-4.9/prebuilt/linux-x86_64 -E

as can be seen by inserting in configure.ac:
AC_MSG_CHECKING([for CPP])
AC_MSG_RESULT([$CPP])

and the shared libraries are named 'module_name.cpython-36m-arm-linux-gnueabi.so'.

OTOH, the 'configure' script runs its own preprocessings with the following idiom:
if (eval "$ac_cpp conftest.$ac_ext") 2>&5 | $EGREP "memchr" >/dev/null 2>&1; then :

where 'ac_cpp' is set to ac_cpp='$CPP $CPPFLAGS'.
So the proposed patch LGTM.

PLATFORM_TRIPLETs are specific to multiarch systems such as debian and should not be relied upon on Android, but they should not be entirely wrong of course.

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nosy: +doko

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue27453>
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