PR sanitizer/69278
	* opts.c (parse_sanitizer_options): For -fsanitize=undefined,
	restore enabling also SANITIZE_UNREACHABLE and SANITIZE_RETURN.

	* g++.dg/ubsan/return-7.C: New test.
	* c-c++-common/ubsan/unreachable-4.c: New test.

From-SVN: r242795