Move ranger only VRP folder to tree-vrp.

Move ranger only VRP folder to tree-vrp.

Consolidate the RVRP folder into a single "execute_vrp" routine that mimics
the format used by the vrp1 and vrp2 passes.  Relocate into the tree-vrp file.

	* gimple-ssa-evrp.c (class rvrp_folder): Move to tree-vrp.c.
	(execute_early_vrp): For ranger only mode, invoke ranger_vrp.
	* tree-vrp.c (class rvrp_folder): Relocate here.
	(execute_ranger_vrp): New.
	* tree-vrp.h (execute_ranger_vrp): Export.