Unify EVRP and VRP folding predicate message.

EVRP issues a message fior folding predicates in a different format than
VRP does, this patch unifies the messaging.

	gcc/
	* vr-values.c (simplify_using_ranges::fold_cond): Change fold message.

	gcc/testsuite/
	* gcc.dg/tree-ssa/evrp9.c: Adjust message scanned for.
	* gcc.dg/tree-ssa/pr21458-2.c: Ditto.