tree-optimization/116902 - vectorizer load hosting breaks UID order #2

tree-optimization/116902 - vectorizer load hosting breaks UID order #2

This is another case of load hoisting breaking UID order in the
preheader, this time between two hoistings.  The easiest way out is
to do what we do for the main stmt - copy instead of move.

	PR tree-optimization/116902
	PR tree-optimization/116842
	* tree-vect-stmts.cc (sort_after_uid): Remove again.
	(hoist_defs_of_uses): Copy defs instead of hoisting them so
	we can zero their UID.
	(vectorizable_load): Separate analysis and transform call,
	do transform on the stmt copy.

	* g++.dg/torture/pr116902.C: New testcase.