re PR sanitizer/59415 (ICE segfault in verify_bb_vtables for g++ -S -fvtable-verify=std -fsanitize=null)

	PR sanitizer/59415
	* vtable-verify.c (verify_bb_vtables): Check the return value
	of gimple_call_fn.  Use is_gimple_call instead of gimple_code.
testsuite/
	* g++.dg/ubsan/pr59415.C: New test.

From-SVN: r205805