Remove vec_stmt from vectorizable_* API

Remove vec_stmt from vectorizable_* API

The following removes the non-SLP gimple **vec_stmt argument from
the vectorizable_* functions API.  Checks on it can be replaced
by an inverted check on the passed cost_vec vector pointer.

	* tree-vectorizer.h (vectorizable_induction): Remove
	gimple **vec_stmt argument.
	(vectorizable_phi): Likewise.
	(vectorizable_recurr): Likewise.
	(vectorizable_early_exit): Likewise.
	* tree-vect-loop.cc (vectorizable_phi): Likewise and adjust.
	(vectorizable_recurr): Likewise.
	(vectorizable_nonlinear_induction): Likewise.
	(vectorizable_induction): Likewise.
	* tree-vect-stmts.cc (vectorizable_bswap): Likewise.
	(vectorizable_call): Likewise.
	(vectorizable_simd_clone_call): Likewise.
	(vectorizable_conversion): Likewise.
	(vectorizable_assignment): Likewise.
	(vectorizable_shift): Likewise.
	(vectorizable_operation): Likewise.
	(vectorizable_store): Likewise.
	(vectorizable_load): Likewise.
	(vectorizable_condition): Likewise.
	(vectorizable_comparison_1): Likewise.
	(vectorizable_comparison): Likewise.
	(vectorizable_early_exit): Likewise.
	(vect_analyze_stmt): Adjust.
	(vect_transform_stmt): Likewise.
	* tree-vect-slp.cc (vect_slp_analyze_operations): Adjust.
	(vectorize_slp_instance_root_stmt): Likewise.