nfs/nlm: use req's uid and gid for open_and_resume

Previously, NLM was setting the frame->root->{uid,gid}
to root by default. This causes permission problems with
root squashing for lock calls. Now, we obtain the uid and
gid from rpc request. And duplicate #defines are removed
from rpcsvc.h

Change-Id: I5d6c87aed8d04aab2619bb913408048c0a02d1e7
BUG: 906884
Signed-off-by: Rajesh Amaravathi <rajesh@redhat.com>
Reviewed-on: http://review.gluster.org/4466
Reviewed-by: Niels de Vos <ndevos@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>