Integrate SLP permute transform into vect_transform_stmt

Integrate SLP permute transform into vect_transform_stmt

This adds permute_info_type and removes the duplication from
vect_schedule_slp_node.

	* tree-vectorizer.h (stmt_vec_info_type::permute_info_type): Add.
	(vectorizable_slp_permutation): Declare.
	* tree-vect-slp.cc (vectorizable_slp_permutation): Export.
	(vect_slp_analyze_node_operations_1): Set permute_info_type
	on permute nodes successfully analyzed.
	(vect_schedule_slp_node): Dispatch to vect_transform_stmt
	for all nodes.
	* tree-vect-stmts.cc (vect_transform_stmt): Remove redundant
	dump, handle permute_info_type.

	* gcc.dg/vect/vect-reduc-chain-2.c: Adjust.
	* gcc.dg/vect/vect-reduc-chain-3.c: Likewise.