Replace @synchronized lock with dispatch_semaphore lock for SDWebImageCombinedOperation
Replace @synchronized lock with dispatch_semaphore lock for SDWebImageCombinedOperation

dreampiggy/SDWebImage,awkward/SDWebImage,dreampiggy/SDWebImage,smule/SDWebImage,tualatrix/SDWebImage,zhang-yawei/SDWebImage,Insfgg99x/SDWebImage,awkward/SDWebImage,dreampiggy/SDWebImage,rs/SDWebImage,awkward/SDWebImage,iheartradio/SDWebImage