re PR libfortran/24991 (gfortran build fails with - error:gthr-default.h: No such...

re PR libfortran/24991 (gfortran build fails with - error:gthr-default.h: No such file or directory)

	PR libfortran/24991
	* acinclude.m4 (LIBGFOR_CHECK_PRAGMA_WEAK): Rename to...
	(LIBGFOR_GTHREAD_WEAK): ... this.  Define SUPPORTS_WEAK rather
	than HAVE_PRAGMA_WEAK.  Define GTHREAD_USE_WEAK to 0 on hosts
	that shouldn't use weak in gthr.h.
	* configure.ac: Use LIBGFOR_GTHREAD_WEAK instead of
	LIBGFOR_CHECK_PRAGMA_WEAK.
	* config.h.in: Regenerated.
	* configure: Regenerated.
	* io/io.h (SUPPORTS_WEAK): Don't define here.

	* intrinsics/ftell.c (ftell, FTELL_SUB): Add unlock_unit call.
	* intrinsics/fget.c (fgetc, fputs): Likewise.
	* intrinsics/tty.c (ttynam): Likewise.

From-SVN: r108471