tree-vrp.c (vrp_visit_phi_node): Allow a last iteration if the currently executable edges have fixed ranges.

2016-08-12  Richard Biener  <rguenther@suse.de>

	* tree-vrp.c (vrp_visit_phi_node): Allow a last iteration if
	the currently executable edges have fixed ranges.  Always
	go through update_value_range.

From-SVN: r239404