* config/mh-lynxrs6k: Renamed from mh-lynxosrs6k, to make it unique in 8.3

* config/mh-lynxrs6k: Renamed from mh-lynxosrs6k, to make it unique in 8.3
naming schemes.
* configure.in (appdirs): New variable.  Currently empty, but will be used in
gas distribution.  If nonempty, lists a set of directories at least one of
which must get configured, or top level configuration is considered to have
failed.
(rs6000-*-lynxos*): Use new file name.