Merge pull request SDWebImage#3474 from dreampiggy/bugfix/atomic_fix

Avoid compiler generate the wrong property attribute with non-atomic

Author: dreampiggy

SDWebImage/Private/SDAsyncBlockOperation.m

@@ -10,8 +10,6 @@
 
 @interface SDAsyncBlockOperation ()
 
-@property (assign, nonatomic, getter = isExecuting) BOOL executing;
-@property (assign, nonatomic, getter = isFinished) BOOL finished;
 @property (nonatomic, copy, nonnull) SDAsyncBlock executionBlock;
 
 @end