darwin-avoid-spinlock

Finds usages of OSSpinlock, which is deprecated due to potential livelock problems.

This check will detect following function invocations:

• OSSpinlockLock
• OSSpinlockTry
• OSSpinlockUnlock

The corresponding information about the problem of OSSpinlock: https://blog.postmates.com/why-spinlocks-are-bad-on-ios-b69fc5221058