tree-optimization/110436 - bogus live/relevant for unused pattern

When we compute liveness and relevantness we have to make sure to
handle live but not relevant stmts in a way we can later vectorize
them.  When the stmt uses only operands that do not need vectorization
we can just leave such stmts in place - but not in the case they
are recognized as patterns.  Since we don't have a way to cancel
pattern recognition we have to force mark such stmts as relevant.

	PR tree-optimization/110436
	* tree-vect-stmts.cc (vect_mark_relevant): Expand dumping,
	force live but not relevant pattern stmts relevant.

	* gcc.dg/pr110436.c: New testcase.