* builtins.c (expand_builtin_strcmp): Defend against the possibility
	that gen_cmpstrsi may fail: Stabilize the argument list against
	re-evaluation and expand the library call directly using this saved
	argument list if a cmpstrsi sequence can't be generated.
	(expand_builtin_strncmp): Likewise.

	* config/i386/i386.md (cmpstrsi, movstrsi): Disable with -Os.

	* gcc.c-torture/execute/string-opt-8.c: Don't test optimizations
	that inline strncmp as cmpstrsi on i386 when compiled with -Os.

From-SVN: r72380