rtl-optimization/105559 - avoid quadratic behavior in delete_insn_and_edges

rtl-optimization/105559 - avoid quadratic behavior in delete_insn_and_edges

When the insn to delete is a debug insn there's no point in figuring
out whether it might be the last real insn and thus we have to purge
dead edges.

2022-05-11  Richard Biener  <rguenther@suse.de>

	PR rtl-optimization/105559
	* cfgrtl.cc (delete_insn_and_edges): Only perform search to BB_END
	for non-debug insns.

(cherry picked from commit 37a8220fa9188470c677abfef50c1b120c0b6c76)