Fix off by one in range_from_loop_direction.

Fix off by one in range_from_loop_direction.

When bounds_of_var_in_loop was converted to range_from_loop_direction,
the final check returned FALSE when the beginning and end bounds were
the same...  The new code was using wi::gt_p, when it should have been
wi::ge_p when checking for the fail condition.

	PR tree-optimization/120560
	gcc/
	* vr-values.cc (range_from_loop_direction): Use wi::ge_p rather
	than wi::gt_p.

	gcc/testsuite/
	* gcc.dg/pr120560.c: New.