OpenBSD: No ruid/rgid in cred structure.

OpenBSD: No ruid/rgid in cred structure.

OpenBSD does not retain ruid or rgid values in the
afs_creds_t structure (ucred). This patch, therefore,
removes any references to them in the afs.h file. Since
no attempt is made to actually use the removed code (or
macros) on OpenBSD, at least at this time, this does
not result in any real functional change.

Change-Id: Iaceb792f0c39ba6f7caa205bc66af16a23193549
Reviewed-on: http://gerrit.openafs.org/3687
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>