mgmt/glusterd: serialize the dict only if its not NULL
mgmt/glusterd: serialize the dict only if its not NULL

Signed-off-by: Pranith Kumar K <pranithk@gluster.com>
Signed-off-by: Vijay Bellur <vijay@gluster.com>

BUG: 2691 ([glusterfs-3.2.0qa9]: glusterd error)
URL: http://bugs.gluster.com/cgi-bin/bugzilla3/show_bug.cgi?id=2691

Kaushikbv/Gluster,Kaushikbv/Gluster,Kaushikbv/Gluster