Remove OS_OBJECT_HAVE_OBJC_SUPPORT conditional compilation

`OS_OBJECT_HAVE_OBJC_SUPPORT` is defined to 1 for iOS deployment target >= 6.0 and OS X deployment target >= 10.8.

AFNetworking/AFURLSessionManager.h

@@ -156,20 +156,12 @@ NS_ASSUME_NONNULL_BEGIN
 /**
  The dispatch queue for `completionBlock`. If `NULL` (default), the main queue is used.
  */
-#if OS_OBJECT_HAVE_OBJC_SUPPORT
 @property (nonatomic, strong, nullable) dispatch_queue_t completionQueue;
-#else
-@property (nonatomic, assign, nullable) dispatch_queue_t completionQueue;
-#endif
 
 /**
  The dispatch group for `completionBlock`. If `NULL` (default), a private dispatch group is used.
  */
-#if OS_OBJECT_HAVE_OBJC_SUPPORT
 @property (nonatomic, strong, nullable) dispatch_group_t completionGroup;
-#else
-@property (nonatomic, assign, nullable) dispatch_group_t completionGroup;
-#endif
 
 ///---------------------------------
 /// @name Working Around System Bugs

UIKit+AFNetworking/AFAutoPurgingImageCache.m

@@ -67,11 +67,7 @@
 @interface AFAutoPurgingImageCache ()
 @property (nonatomic, strong) NSMutableDictionary <NSString* , AFCachedImage*> *cachedImages;
 @property (nonatomic, assign) UInt64 currentMemoryUsage;
-#if OS_OBJECT_HAVE_OBJC_SUPPORT
 @property (nonatomic, strong) dispatch_queue_t synchronizationQueue;
-#else
-@property (nonatomic, assign) dispatch_queue_t synchronizationQueue;
-#endif
 @end
 
 @implementation AFAutoPurgingImageCache

UIKit+AFNetworking/AFImageDownloader.m

@@ -93,13 +93,8 @@
 
 @interface AFImageDownloader ()
 
-#if OS_OBJECT_HAVE_OBJC_SUPPORT
 @property (nonatomic, strong) dispatch_queue_t synchronizationQueue;
 @property (nonatomic, strong) dispatch_queue_t responseQueue;
-#else
-@property (nonatomic, assign) dispatch_queue_t synchronizationQueue;
-@property (nonatomic, assign) dispatch_queue_t responseQueue;
-#endif
 
 @property (nonatomic, assign) NSInteger maximumActiveDownloads;
 @property (nonatomic, assign) NSInteger activeRequestCount;