re PR target/19019 (GCC ldouble format incompatibility with XLC long double)

re PR target/19019 (GCC ldouble format incompatibility with XLC long double)

	PR target/19019
	* Makefile.in (LIB2FUNCS_SHARED_EXTRA, LIB2ADD_SH): New.
	(libgcc.mk): Depend on $(LIB2ADD_SH), pass LIB2ADD_SH to mklibgcc.
	(LIBGCC_DEPS): Add $(LIB2ADD_SH).
	* mklibgcc.in: Handle LIB2ADD_SH.
	* config/rs6000/t-linux64 (LIB2FUNCS_EXTRA): Remove darwin-ldouble.c.
	(LIB2FUNCS_STATIC_EXTRA, LIB2FUNCS_SHARED_EXTRA): Set.
	* config/rs6000/darwin-ldouble.c: Protect .symver asm also with
	defined IN_LIBGCC2_S.
	* config/rs6000/darwin-ldouble-shared.c: New file.

From-SVN: r95495