If some implementations don't support this operation, it might indicate it isn't necessary. I only know pthread mutex functions don't provide such a method, and I'm somewhat confident that they provide thoroughly thought-out APIs. I also can't think of a use case. Either I need to work on a resource that needs to be locked, then I lock the mutex. If I get it fine. If I don't get it (maybe within a given time), what can I do? Nothing. I'll have to exit.
So what's the reason for checking the status of a mutex?