tree-optimization/108825 - checking ICE with unroll-and-jam

tree-optimization/108825 - checking ICE with unroll-and-jam

The issue is that unroll-and-jam applies RPO VN on the transformed body but
that leaves the IL in "indetermined" state (it returns a TODO to make it
valid again).  But unroll-and-jam then continues to transform another loop and
in using the tree_unroll_loop helper runs into tree_transform_and_unroll_loop
performing IL checking on the whole function.

While the real fix is to elide all such checking I'm only making the
loop-local LC SSA verifier not perform function-wide SSA verification
at this point.

	PR tree-optimization/108825
	* tree-ssa-loop-manip.cc (verify_loop_closed_ssa): For
	loop-local verfication only verify there's no pending SSA
	update.

	* gcc.dg/torture/pr108825.c: New testcase.