[PATCH][PR tree-optimization/67816] Fix jump threading when DOM removes conditionals in jump threading path

	PR tree-optimization/67816
	* tree-ssa-threadupdate.h (remove_jump_threads_including): Renamed
	from remove_jump_threads_starting_at.  Accept an edge rather than
	a basic block.
	* tree-ssa-threadupdate.c (removed_edges): New hash table.
	(remove_jump_threads_including): Note edges that get removed from
	the CFG for later pruning of jump threading paths including them.
	(thread_through_all_blocks): Remove paths which include edges that
	have been removed.
	* tree-ssa-dom.c (optimize_stmt): Call remove_jump_threads_including
	on each outgoing edges when optimizing away a control statement.

	* gcc.c-torture/compile/pr67816.c: New test.

From-SVN: r228559