VF_MPI Compiler Definition
In this commit we added the specification that VF_MPI is only set when the CPU Version of VF is build: https://git.rz.tu-bs.de/m.schoenherr/VirtualFluids_dev/-/commit/8ef05231c901e81f3960c601ef5cc9855189b152
The reason was, that this flag caused problems in the gpu part. However this potential bug can not be reproduced anymore. Thats why I decided to revert those changes in: https://git.rz.tu-bs.de/irmb/VirtualFluids_dev/-/commit/7c87f021535dca8cfff20b9d5b4390866a1bcf20
However, if this problems appear again we should find the error source.