Various cleanups in vr-values.cc towards ranger API.

Various cleanups in vr-values.cc towards ranger API.

gcc/ChangeLog:

	* vr-values.cc (check_for_binary_op_overflow): Tidy up by using
	ranger API.
	(compare_ranges): Delete.
	(compare_range_with_value): Delete.
	(bounds_of_var_in_loop): Tidy up by using ranger API.
	(simplify_using_ranges::fold_cond_with_ops): Cleanup and rename
	from vrp_evaluate_conditional_warnv_with_ops_using_ranges.
	(simplify_using_ranges::legacy_fold_cond_overflow): Remove
	strict_overflow_p and only_ranges.
	(simplify_using_ranges::legacy_fold_cond): Adjust call to
	legacy_fold_cond_overflow.
	(simplify_using_ranges::simplify_abs_using_ranges): Adjust for
	rename.
	(range_fits_type_p): Rename value_range to irange.
	* vr-values.h (range_fits_type_p): Adjust prototype.