PR c/71512
	* ubsan.c (instrument_si_overflow): Pass true instead of false
	to gsi_replace.
	(pass_ubsan::execute): Call gimple_purge_dead_eh_edges at the end
	of bbs.  Return TODO_cleanup_cfg if any returned true.

	* g++.dg/ubsan/pr71512.C: New test.
	* c-c++-common/ubsan/pr71512-1.c: New test.
	* c-c++-common/ubsan/pr71512-2.c: New test.

From-SVN: r239430