Fix minor compilation issues on rel-2-2-8

This fixes an accidental introduction of a C++11 feature into rel-2-2-x with 3744b480.

Also, there were some MPI_Init that still used a removed custom interface for the argument types. This was overlooked in the 5b5206c9 commit (by me 🤷) because they are not usually compiled. These calls are now adapted to (also) use the proper types.

Please also apply 076c370d to master when accepting this MR to port the MPI_Init fixes.