Remove pass counting in VRP.

Remove pass counting in VRP.

Rather than using a pass count to decide which parameters are passed to
VRP, makemit explicit.

	* passes.def (pass_vrp): Pass "final pass" flag as parameter.
	* tree-vrp.cc (vrp_pass_num): Remove.
	(pass_vrp::my_pass): Remove.
	(pass_vrp::pass_vrp): Add warn_p as a parameter.
	(pass_vrp::final_p): New.
	(pass_vrp::set_pass_param): Set final_p param.
	(pass_vrp::execute): Call execute_range_vrp with no conditions.
	(make_pass_vrp): Pass additional parameter.
	(make_pass_early_vrp): Ditto.