Remove the unused define

Code typo fix

SDWebImageWebPCoder/Classes/SDImageWebPCoder.m

@@ -100,14 +100,6 @@ static CGSize SDCalculateThumbnailSize(CGSize fullSize, BOOL preserveAspectRatio
     return CGSizeMake(resultWidth, resultHeight);
 }
 
-#ifndef SD_LOCK
-#define SD_LOCK(lock) dispatch_semaphore_wait(lock, DISPATCH_TIME_FOREVER);
-#endif
-
-#ifndef SD_UNLOCK
-#define SD_UNLOCK(lock) dispatch_semaphore_signal(lock);
-#endif
-
 @interface SDWebPCoderFrame : NSObject
 
 @property (nonatomic, assign) NSUInteger index; // Frame index (zero based)