ranges: introduce rl_invert(), rl_filter() and rl_intersection()

ranges: introduce rl_invert(), rl_filter() and rl_intersection()

Some new helper functions for manipulating range_lists.  I will use them in
a later patch.

rl_invert() takes a range list and gives you the opposite ranges.
rl_filter() takes two ranges lists and returns everything that is in the
            first but not in the second.
rl_intersection() takes two range lists and returns what ever is in both.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>