Since Android NDK r14 beta 2, unified headers provide langinfo.h but there's no nl_langinfo() in it, causing linking failures:

libpython3.7m.a(pylifecycle.o): In function `get_locale_encoding':
/home/yen/Projects/python3-android/src/cpython/Python/pylifecycle.c:234: undefined reference to `nl_langinfo'
libpython3.7m.a(fileutils.o): In function `_Py_device_encoding':
/home/yen/Projects/python3-android/src/cpython/Python/fileutils.c:65: undefined reference to `nl_langinfo'
libpython3.7m.a(_localemodule.o): In function `PyLocale_nl_langinfo':
/home/yen/Projects/python3-android/src/cpython/./Modules/_localemodule.c:447: undefined reference to `nl_langinfo'

Or compiler errors due to implicit function declarations if the patch at issue22747 is applied.

nl_langinfo.patch fixes it by adding some extra guarding macros.

Added some people from issue22747 to the nosy list, where the last change about langinfo.h and Android occurred.