remove unnecessary calls to vec::release

remove unnecessary calls to vec::release

There's no point in calling release () on an auto_vec just before it goes
out of scope.

gcc/ChangeLog:

2016-07-12  Trevor Saunders  <tbsaunde+gcc@tbsaunde.org>

	* tree-data-ref.c (find_data_references_in_stmt): Remove
	unnecessary call to vec::release.
	(graphite_find_data_references_in_stmt): Likewise.
	* tree-ssa-alias.c (nonoverlapping_component_refs_of_decl_p): Likewise.
	* tree-vect-stmts.c (vectorizable_condition): Likewise.

From-SVN: r238286