Remove insert location argument from vectorizable_live_operation

The insert location argument isn't actually used but we compute
that ourselves.  There's a single spot, namely when asking
for the loop mask via vect_get_loop_mask that the passed argument
is used but that looks like an oversight.  The following fixes that
and adjusts vectorizable_live_operation and can_vectorize_live_stmts
to no longer take a stmt iterator argument.

	* tree-vectorizer.h (vectorizable_live_operation): Remove
	gimple_stmt_iterator * argument.
	* tree-vect-loop.cc (vectorizable_live_operation): Likewise.
	Adjust plumbing around vect_get_loop_mask.
	(vect_analyze_loop_operations): Adjust.
	* tree-vect-slp.cc (vect_slp_analyze_node_operations_1): Likewise.
	(vect_bb_slp_mark_live_stmts): Likewise.
	(vect_schedule_slp_node): Likewise.
	* tree-vect-stmts.cc (can_vectorize_live_stmts): Likewise.
	Remove gimple_stmt_iterator * argument.
	(vect_transform_stmt): Adjust.