tree-vrp.c (set_value_range): Use vrp_equiv_obstack with BITMAP_ALLOC.

tree-vrp.c (set_value_range): Use vrp_equiv_obstack with BITMAP_ALLOC.

gcc/ChangeLog:

2016-08-04  Kugan Vivekanandarajah  <kuganv@linaro.org>

	* tree-vrp.c (set_value_range): Use vrp_equiv_obstack with
	BITMAP_ALLOC.
	(add_equivalence): Likewise.
	(get_value_range): Allocate value range with vrp_value_range_pool.
	(vrp_initialize): Initialize vrp_equiv_obstack for equiv allocation.
	(vrp_finalize): Relase vrp_equiv_obstack and vrp_value_range_pool.

From-SVN: r239113