path solver: Avoid further lookups when range is defined in block.

path solver: Avoid further lookups when range is defined in block.

If an SSA is defined in the current block, there is no need to query
range_on_path_entry for additional information.

gcc/ChangeLog:

	* gimple-range-path.cc (path_range_query::path_range_query):
	Move debugging header...
	(path_range_query::precompute_ranges): ...here.
	(path_range_query::internal_range_of_expr): Do not call
	range_on_path_entry if NAME is defined in the current block.