Semaphore not implemented?

I’m trying to implement threads into my c++ code to run async lua scripts. For this I need a mutex or semaphore which is usable on all platforms(Windows and linux at least).
So I tried to use “FGenericPlatformProcess” but there I always get an “not implemented” error.
For Windows I can use “FPlatformProcess”, but like I said I would need it also for linux.

Is there nothing in the unreal engine 4.5.1?

mutex = FGenericPlatformProcess::NewInterprocessSynchObject("mutex", true, 1); 

Fatal error:
[Line: 434]
not implemented on this platform

This was asked forever ago. Where is the support? Bump. I need this for more than a single platform.