Fix leak in GPUImageContext BradLarson#2549

Author: Ethan-Z

framework/Source/iOS/GPUImageContext.m

@@ -44,6 +44,13 @@ - (id)init;
     return self;
 }
 
+- (void)dealloc {
+    if (_coreVideoTextureCache != NULL) {
+        CFRelease(_coreVideoTextureCache);
+    }
+}
+
+
 + (void *)contextKey {
 	return openGLESContextQueueKey;
 }