VRP: Simplify logic for checking if any asserts need to be inserted

VRP: Simplify logic for checking if any asserts need to be inserted

2014-11-11  Patrick Palka  <ppalka@gcc.gnu.org>

	* tree-vrp.c (register_edge_assert_for_2): Change return type to
	void and adjust accordingly.
	(register_edge_assert_for_1): Likewise.
	(register_edge_assert_for): Likewise.
	(find_conditional_asserts): Likewise.
	(find_switch_asserts): Likewise.
	(find_assert_locations_1): Likewise.
	(find_assert_locations): Likewise.
	(insert_range_insertions): Inspect the need_assert_for bitmap.

From-SVN: r217400