Convert -Walloca pass to ranger.

Convert -Walloca pass to ranger.

gcc/ChangeLog:

	* gimple-ssa-warn-alloca.c (enum alloca_type): Remove
	ALLOCA_BOUND_UNKNOWN and ALLOCA_CAST_FROM_SIGNED.
	(warn_limit_specified_p): New.
	(alloca_call_type_by_arg): Remove.
	(cast_from_signed_p): Remove.
	(is_max): Remove.
	(alloca_call_type): Remove heuristics and replace with call into
	ranger.
	(pass_walloca::execute): Instantiate ranger.

gcc/testsuite/ChangeLog:

	* gcc.dg/Walloca-1.c: Adjust for ranger.
	* gcc.dg/Walloca-12.c: Same.
	* gcc.dg/Walloca-13.c: Same.
	* gcc.dg/Walloca-2.c: Same.
	* gcc.dg/Walloca-3.c: Same.
	* gcc.dg/Walloca-6.c: Same.
	* gcc.dg/Wvla-larger-than-2.c: Same.