gh-99942: python.pc on android/cygwin should link to libpython per configure.ac (GH-100356)

In commit 254b309 a previous change to avoid linking to libpython was partially reverted for Android (and later Cygwin as well), to add back the link flags. This was applied to distutils and to python-config.sh, but not to python.pc.

Add it back to python.pc as well.

Automerge-Triggered-By: GH:gpshead

Author: eli-schwartz

Diff for: Misc/NEWS.d/next/Build/2022-12-20-01-06-17.gh-issue-99942.lbmzYj.rst

@@ -0,0 +1,2 @@
+On Android, python.pc now correctly reports the library to link to, the same
+as python-config.sh.

Diff for: Misc/python.pc.in

@@ -9,5 +9,5 @@ Description: Build a C extension for Python
 Requires:
 Version: @VERSION@
 Libs.private: @LIBS@
-Libs:
+Libs: -L${libdir} @LIBPYTHON@
 Cflags: -I${includedir}/python@VERSION@@ABIFLAGS@