re PR tree-optimization/50682 (ICE: SIGSEGV in main_block_label with -O2 -fnon-call-exceptions -ftracer)

	PR tree-optimization/50682
	* tree-eh.c (maybe_remove_unreachable_handlers): New function.
	* tree-flow.h (maybe_remove_unreachable_handlers): New prototype.
	* tree-optimize.c (execute_cleanup_cfg_post_optimizing): Call it.

	* g++.dg/opt/pr50682.C: New test.

From-SVN: r181785