The old terminology of "toss" and "keep" is no longer an
accurate description of the rsb states and lists, so change
the names to "inactive" and "active".  The old names had
also been copied into the scanning code, which is changed
back to use the "scan" name.

- "active" rsb structs have lkb's attached, and are ref counted.
- "inactive" rsb structs have no lkb's attached, are not ref counted.
- "scan" list is for rsb's that can be freed after a timeout period.
- "slow" lists are for infrequent iterations through active or
   inactive rsb structs.
- inactive rsb structs that are directory records will not be put
  on the scan list, since they are not freed based on timeouts.
- inactive rsb structs that are not directory records will be
  put on the scan list to be freed, since they are not longer needed.
Signed-off-by: David Teigland <teigland@redhat.com>