Do not ignore UNDEFINED ranges when determining PHI equivalences.

Do not ignore UNDEFINED name arguments when registering two-way equivalences
from PHIs.

	PR tree-optimization/109564
	gcc/
	* gimple-range-fold.cc (fold_using_range::range_of_phi): Do no ignore
	UNDEFINED range names when deciding if all PHI arguments are the same,

	gcc/testsuite/
	* gcc.dg/torture/pr109564-1.c: New testcase.
	* gcc.dg/torture/pr109564-2.c: Likewise.
	* gcc.dg/tree-ssa/evrp-ignore.c: XFAIL.
	* gcc.dg/tree-ssa/vrp06.c: Likewise.

(cherry picked from commit 17aa9ddb)