Remove SpinLock because it's illegal in iOS

Author: Adlai-Holler

AsyncDisplayKit/Details/ASThread.h

@@ -195,39 +195,6 @@ namespace ASDN {
   typedef Locker<StaticMutex> StaticMutexLocker;
   typedef Unlocker<StaticMutex> StaticMutexUnlocker;
 
-  struct SpinLock
-  {
-    SpinLock &operator= (bool value) {
-      _l = value ? ~0 : 0; return *this;
-    }
-
-    SpinLock() { _l = OS_SPINLOCK_INIT; }
-    SpinLock(const SpinLock&) = delete;
-    SpinLock &operator=(const SpinLock&) = delete;
-
-    bool try_lock () {
-      return OSSpinLockTry (&_l);
-    }
-
-    void lock () {
-      OSSpinLockLock(&_l);
-    }
-
-    void unlock () {
-      OSSpinLockUnlock(&_l);
-    }
-
-    OSSpinLock *spinlock () {
-      return &_l;
-    }
-
-  private:
-    OSSpinLock _l;
-  };
-
-  typedef Locker<SpinLock> SpinLocker;
-  typedef Unlocker<SpinLock> SpinUnlocker;
-
   struct Condition
   {
     Condition () {