Fix build warning. (no_r=me)

--HG--
extra : rebase_source : cd1afe2f1e8597fb88ca530912dbd6008e3ee9f7

js/src/jsapi.cpp

@@ -1109,11 +1109,6 @@ JS_SetOptions(JSContext *cx, uint32 options)
     AutoLockGC lock(cx->runtime);
     uint32 oldopts = cx->options;
     cx->options = options;
-#if DEBUG
-    bool changedVersion =   
-#else
-    (void)
-#endif
     SyncOptionsToVersion(cx);
     cx->updateJITEnabled();
     CheckOptionVersionSync(cx);