Range_on_edge in ranger_cache should return true for all ranges.

Range_on_edge in ranger_cache should return true for all ranges.

Range_on_edge was implemented in the cache to always return a range, but
only returned true when the edge actally changed the range.
Return true with any range that can be calculated.

	* gimple-range-cache.cc (ranger_cache::range_on_edge): Always return
	true when a range can be calculated.
	* gimple-range.cc (gimple_ranger::dump_bb): Check has_edge_range_p.