tree-optimization/105763 - avoid abnormals with ranger queries

In unswitching we use ranger to simplify switch statements so we
have to avoid doing anything for abnormals.

2022-05-30  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/105763
	* tree-ssa-loop-unswitch.cc (find_unswitching_predicates_for_bb):
	Check gimple_range_ssa_p.

	* gcc.dg/pr105763.c: New testcase.