get_address_ranges() and get_ranges() perform almost the same computation.
They return the same ranges -- the only difference is that
get_address_ranges() returns them in unspecified order, while get_ranges()
returns them in sorted order. Therefore the result of get_ranges() is also
a valid result for get_address_ranges(), and the two functions can be unified
to avoid code duplication. This patch does just that.
5edf965526