Bug 577916 - mark DEBUG only variables as ifdef DEBUG in plugins r=josh a=jst

modules/plugin/base/src/nsNPAPIPlugin.cpp

@@ -1517,7 +1517,10 @@ _retainobject(NPObject* npobj)
     NPN_PLUGIN_LOG(PLUGIN_LOG_ALWAYS,("NPN_retainobject called from the wrong thread\n"));
   }
   if (npobj) {
-    int32_t refCnt = PR_AtomicIncrement((PRInt32*)&npobj->referenceCount);
+#ifdef DEBUG
+    int32_t refCnt =
+#endif
+      PR_AtomicIncrement((PRInt32*)&npobj->referenceCount);
     NS_LOG_ADDREF(npobj, refCnt, "BrowserNPObject", sizeof(NPObject));
   }