glusterd: NULL pointer dereferencing clang fix

Added ternary operator to avoid NULL pointer dereferencing

Updates: bz#1622665

Change-Id: I4b970176b6b555c2eda1da2848c493e45b1e4217
Signed-off-by: Sheetal Pamecha <sheetal.pamecha08@gmail.com>

xlators/mgmt/glusterd/src/glusterd-geo-rep.c

@@ -1677,7 +1677,8 @@ glusterd_update_slave_voluuid_slaveinfo (glusterd_volinfo_t *volinfo)
 
         ret = 0;
 out:
-        gf_msg_debug (this->name, 0, "Returning %d", ret);
+        gf_msg_debug ((this ? this->name : "glusterd"),
+                      0, "Returning %d", ret);
         return ret;
 }