PR libfortran/47571 * acinclude.m4 (LIBGFOR_GTHREAD_WEAK): Remove. (LIBGFOR_CHECK_WEAKREF): New test. * configure.ac: Call LIBGFOR_CHECK_WEAKREF instead of LIBGFOR_GTHREAD_WEAK. * config.h.in: Regenerate. * configure: Regenerate. * intrinsics/system_clock.c: Use SUPPORTS_WEAKREF instead of SUPPORTS_WEAK and GTHREAD_USE_WEAK. From-SVN: r227335