SLP: support entire BB.

SLP: support entire BB.

gcc/ChangeLog:

	* tree-vect-data-refs.c (dr_group_sort_cmp): Work on
	data_ref_pair.
	(vect_analyze_data_ref_accesses): Work on groups.
	(vect_find_stmt_data_reference): Add group_id argument and fill
	up dataref_groups vector.
	* tree-vect-loop.c (vect_get_datarefs_in_loop): Pass new
	arguments.
	(vect_analyze_loop_2): Likewise.
	* tree-vect-slp.c (vect_slp_analyze_bb_1): Pass argument.
	(vect_slp_bb_region): Likewise.
	(vect_slp_region): Likewise.
	(vect_slp_bb):Work on the entire BB.
	* tree-vectorizer.h (vect_analyze_data_ref_accesses): Add new
	argument.
	(vect_find_stmt_data_reference): Likewise.

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/bb-slp-38.c: Adjust pattern as now we only process
	a single vectorization and now 2 partial.
	* gcc.dg/vect/bb-slp-45.c: New test.