check if GPU was used if job requested a GPU

[kain88-de]

The gromacs logs are nicely verbose. We can actually use them to check if there was a GPU detected on the main node and if it was used during the simulation. This would help with better error reporting about how the jobs have finished.

[mimischi]

We can do this easily, because GROMACS tells us if it has not found any GPUs to use.

I just do not see how this is useful or where to show it to the user.