tree-optimization/105142 - improve maybe_fold_comparisons_from_match_pd fix

tree-optimization/105142 - improve maybe_fold_comparisons_from_match_pd fix

The following improves on the fix for PR105142 which restricted the
expression lookup used for maybe_fold_comparisons_from_match_pd to
avoid picking up flow-sensitive info for use in places where guarding
conditions do not hold.  Instead of not allowing to expand SSA
definitions there the following temporarily clears flow-sensitive
info on the SSA names and restores it when finished matching.

	PR tree-optimization/105142
	* gimple-fold.cc (fosa_unwind): New global.
	(follow_outer_ssa_edges): When the SSA definition to follow
	is does not dominate fosa_bb, temporarily clear flow-sensitive
	info.  Make sure to not expand stmts with not defined overflow.
	(maybe_fold_comparisons_from_match_pd): Set up unwind stack
	for follow_outer_ssa_edges and unwind flow-sensitive info
	clearing after matching.