Support if statement in !GCC$ builtin directive.

Support if statement in !GCC$ builtin directive.

2019-02-18  Martin Liska  <mliska@suse.cz>

	* config/i386/i386.c (ix86_get_multilib_abi_name): New function.
	(TARGET_GET_MULTILIB_ABI_NAME): New macro defined.
	* doc/tm.texi: Document new target hook.
	* doc/tm.texi.in: Likewise.
	* target.def: Add new target macro.
	* gcc.c (find_fortran_preinclude_file): Do not search multilib
	suffixes.
2019-02-18  Martin Liska  <mliska@suse.cz>

	* decl.c (gfc_match_gcc_builtin): Add support for filtering
	of builtin directive based on multilib ABI name.
2019-02-18  Martin Liska  <mliska@suse.cz>

	* gfortran.dg/simd-builtins-7.f90: New test.
	* gfortran.dg/simd-builtins-7.h: New test.

From-SVN: r268978