features/changelog: Fixing Deference after null check

CID: 1124481
The goto label 'out' was trying to
dereference a pointer which might be
null, hence a check on not null is
made before the use of it.

Change-Id: I813e523207b8218a7a28c2b3ac36a8e472e36c89
BUG: 789278
Signed-off-by: arao <arao@redhat.com>
Reviewed-on: http://review.gluster.org/9617
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

xlators/features/changelog/src/changelog.c

@@ -2376,7 +2376,7 @@ reconfigure (xlator_t *this, dict_t *options)
         } else {
                 gf_log (this->name, GF_LOG_DEBUG,
                         "changelog reconfigured");
-                if (active_now)
+                if (active_now && priv)
                         priv->active = _gf_true;
         }