Skip semaphore test

Currently the OBS VMs used for building arm targets don't have /dev/shm mounted, this results in the Python configure script disabling POSIX semaphores at compile time, which in turn means that the multiprocessing module isn't available at runtime on real devices (which do have /dev/shm available).

This can be tested by running:

```
>>> import multiprocessing
>>> multiprocessing.Event()
```

Which will result in the following error with the current builds of Python 3:

```
Traceback (most recent call last):
  File "/usr/lib/python3.3/multiprocessing/synchronize.py", line 27, in <module>
    from _multiprocessing import SemLock
ImportError: cannot import name SemLock

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python3.3/multiprocessing/__init__.py", line 186, in Event
    from multiprocessing.synchronize import Event
  File "/usr/lib/python3.3/multiprocessing/synchronize.py", line 32, in <module>
    " function, see issue 3770.")
ImportError: This platform lacks a functioning sem_open implementation, therefore, the required synchronization primitives needed will not function, see issue 3770.
```

This merge request adds a patch which causes the semaphore tests to always succeed, making it possible to use the multiprocessing module on real devices:

```
>>> import multiprocessing
>>> multiprocessing.Event()
<multiprocessing.synchronize.Event object at 0x40235bd0>
```

Thanks,
Mike.