Vector peeling cost model 2/6

gcc/ChangeLog:

2017-05-30  Robin Dapp  <rdapp@linux.vnet.ibm.com>

	* tree-vect-data-refs.c (vect_update_misalignment_for_peel): Rename.
	(vect_get_peeling_costs_all_drs): Create function.
	(vect_peeling_hash_get_lowest_cost):
	Use vect_get_peeling_costs_all_drs.
	(vect_peeling_supportable): Create function.
	(vect_enhance_data_refs_alignment): Use vect_peeling_supportable.

From-SVN: r248676