internal-fn.c: Include stringpool.h and tree-ssanames.h.

internal-fn.c: Include stringpool.h and tree-ssanames.h.

	* internal-fn.c: Include stringpool.h and tree-ssanames.h.
	(ubsan_expand_si_overflow_addsub_check): In the generic expansion,
	try to improve generated code if one of the arguments is constant
	or get_range_info says that one of the argument is always
	negative or always non-negative.
	* tree-vrp.c (simplify_internal_call_using_ranges): New function.
	(simplify_stmt_using_ranges): Call it.

From-SVN: r206025