destroy pthread_mutex on dealloc: #30

YYCache/YYMemoryCache.m

@@ -352,6 +352,7 @@ static inline dispatch_queue_t YYMemoryCacheGetReleaseQueue() {
     [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
     [[NSNotificationCenter defaultCenter] removeObserver:self name:UIApplicationDidEnterBackgroundNotification object:nil];
     [_lru removeAll];
+    pthread_mutex_destroy(&_lock);
 }
 
 - (NSUInteger)totalCount {