Adapt OpenACC+MPI GPU test

[vkarak]

MCH will provide an updated version of the test's source code:

https://github.com/eth-cscs/reframe/blob/master/cscs-checks/prgenv/src/gpu_direct_acc.f90

Also the filename is not accurate.

[lxavier]

see #281

[vkarak]

Hi @lxavier, I'd suggest putting a reference in the corresponding pull request's description rather than here (Github tracks the references automatically). Also, if your PR fixes this issue, simply put in the description the following text Fixes #247, so that Github will automatically close the issue as soon as we merge it.

[vkarak]

Quoting from @lxavier about running the test:

nothing special I would start to run it on one node (e.g. 8 GPUs on Kesch) just did srun -n 8
The important thing is to load the module that we use. Since our new module generator is not yet ready you could use the module file on /project /project/c14/install/kesch/cosmo5/modules_fortran_gpu_double.env