convert.c (convert_to_integer): Don't instrument conversions if the function has no_sanitize_undefined attribute.

	* convert.c (convert_to_integer): Don't instrument conversions if the
	function has no_sanitize_undefined attribute.
	* ubsan.c: Don't run the ubsan pass if the function has
	no_sanitize_undefined attribute.
c/
	* c-decl.c (grokdeclarator): Don't instrument VLAs if the function
	has no_sanitize_undefined attribute.
cp/
	* cp-gimplify.c (cp_genericize): Don't instrument returns if the
	function has no_sanitize_undefined attribute.
	* decl.c (compute_array_index_type): Don't instrument VLAs if the
	function has no_sanitize_undefined attribute.
testsuite/
	* c-c++-common/ubsan/attrib-2.c: New test.
	* g++.dg/ubsan/return-3.C: New test.

From-SVN: r212148