bozo: do not fail silently on unknown bosserver options

bozo: do not fail silently on unknown bosserver options

Instead of failing silently when the bosserver is started with an
unknown option, print an error message and exit with a non-zero value.
Continue to exit with 0 when the -help option is given to request the
usage message.

This change should help make bosserver startup failures more obvious
when an unsupported option is specified. Example systemd status message:

   systemd[1]: Starting OpenAFS Server Service...
   bosserver[32308]: Unrecognized option: -bogus
   bosserver[32308]: Usage: bosserver [-noauth] ....
   systemd[1]: openafs-server.service: main process exited,
               code=exited, status=1/FAILURE

Change-Id: I8717fb4a788fbcc3d1e2d271dd03511c5b504f10
Reviewed-on: https://gerrit.openafs.org/12630
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>