Pass multi-range from range_query::value_* routines

fix range-ops equal/not_equal to not reuse the result range as intermediary.
value_query::value routines should pasa multi-range in as some other rangeop
routines build into this result, so we may need better precision.

	gcc/
	PR tree-optimization/97725
	* range-op.cc (operator_equal::fold_range): Use new tmp value.
	(operator_not_equal::fold_range): Ditto.
	* value-query.cc (range_query::value_of_expr): Use int_range_max
	not a value_range.
	(range_query::value_on_edge): Ditto.
	(range_query::value_of_stmt): Ditto.
	gcc/testsuite/
	* gcc.dg/pr97725.c: New.