path solver: Use range_on_path_entry instead of looking at equivalences.

path solver: Use range_on_path_entry instead of looking at equivalences.

Cycling through equivalences to improve a range is nowhere near as
efficient as asking the ranger what the range on entry is.

Testing on a hybrid VRP threader, shows that this improves our VRP
threading benefit from 14.5% to 18.5% and our overall jump threads from
0.85% to 1.28%.

Tested on x86-64 Linux.

gcc/ChangeLog:

	* gimple-range-path.cc (path_range_query::internal_range_of_expr):
	Remove call to improve_range_with_equivs.
	(path_range_query::improve_range_with_equivs): Remove
	* gimple-range-path.h: Remove improve_range_with_equivs.