Centralize PICFLAG configuration

Centralize PICFLAG configuration

	config:
	* picflag.m4: New file.

	gcc:
	* configure.ac (GCC_PICFLAG_FOR_TARGET): Call it.
	(PICFLAG_FOR_TARGET): Substitute.
	* aclocal.m4: Regenerate.
	* configure: Regenerate.

	gcc/ada:
	* gcc-interface/Makefile.in (PICFLAG_FOR_TARGET): New.
	(GNATLIBCFLAGS_FOR_C): Replace
	TARGET_LIBGCC2_CFLAGS by PICFLAG_FOR_TARGET.
	(gnatlib-shared-default, gnatlib-shared-dual-win32)
	(gnatlib-shared-win32, gnatlib-shared-darwin, gnatlib-shared)
	(gnatlib-sjlj, gnatlib-zcx): Likewise.

	libada:
	* configure.ac: Include ../config/picflag.m4.
	(GCC_PICFLAG): Call it.
	Substitute.
	* configure: Regenerate.
	* Makefile.in (TARGET_LIBGCC2_CFLAGS): Replace by PICFLAG.
	(GNATLIBCFLAGS_FOR_C): Replace TARGET_LIBGCC2_CFLAGS by PICFLAG.
	(LIBADA_FLAGS_TO_PASS): Pass PICFLAG as PICFLAG_FOR_TARGET.
	Don't include $(GCC_DIR)/libgcc.mvars.

	libiberty:
	* aclocal.m4: Include ../config/picflag.m4.
	* configure.ac (GCC_PICFLAG): Call it.
	(enable_shared): Clear PICFLAG unless shared.
	* configure: Regenerate.

From-SVN: r177967