Relates to the request in #15900.

Container that represents a resource with reference counting capabilities. Provides operations to suspend acquisition of new references. Useful for resource management when resources are intermittently unavailable.

Using a fair semaphore is based on the following (tested) observations:

• as long as permits can be freely acquired, no noticeable performance difference between fair and non-fair version of semaphore.
• when suspending acquisition of new references, it is important that the process acquiring all locks does not starve. This can only be guaranteed by fair semaphore.
• the given implementation does 10 million (acquire, release) operations per second on my laptop (tested with 50 concurrent threads). Should be fast enough ;-)