rpcsvc: fix dangerous setting of pointer on free'd structure.

Change-Id: I6b666115a8ce155563078d7fc476d41486bab54f
BUG: 884452
Signed-off-by: Vijay Bellur <vbellur@redhat.com>
Reviewed-on: http://review.gluster.org/4995
Reviewed-by: Krishnan Parthasarathi <kparthas@redhat.com>
Reviewed-by: Jeff Darcy <jdarcy@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>