re PR sanitizer/81212 (-Wreturn-type is disabled when used together with -fsanitize...

re PR sanitizer/81212 (-Wreturn-type is disabled when used together with -fsanitize=return)

	PR c++/81212
	* tree-cfg.c (pass_warn_function_return::execute): Handle
	__builtin_ubsan_handle_missing_return like __builtin_unreachable
	with BUILTINS_LOCATION.

	* g++.dg/ubsan/pr81212.C: New test.
	* g++.dg/ubsan/return-1.C: Add -Wno-return-type to dg-options.
	* g++.dg/ubsan/return-2.C: Likewise.
	* g++.dg/ubsan/return-7.C: Likewise.

From-SVN: r255354