The Settings test attempts to test the class by changing settings
variables and reading them back again. Problem is, that affects
the REST of the unit tests. So instead of enabling HW accel and
causing crashes, we'll diddle something innocuous, like OMP_THREADS.
Removing the decode setting makes hardware supported decode break.
There must be some hidden dependency on that variable somewhere
which might also be responsible for the problems with nVidia on
Linux. TODO Remove the dependency
