Fixed #if line for iOS7. Previous version occurs memory leaking on iOS7,...

... because there wasn't called dispatch_release(imageUpdateSemaphore) and libdispatch.dylib's malloc wasn't released.
![screenshot 2013-10-06 18 21 06](https://f.cloud.github.com/assets/988216/1276497/19c785b2-2e6f-11e3-9dc1-3a770b524120.png)
![screenshot 2013-10-06 18 21 11](https://f.cloud.github.com/assets/988216/1276498/1fb801fe-2e6f-11e3-9712-9fdd45b0446e.png)