Add missing MPI size in non-MPI mode
Add missing MPI size in non-MPI mode

Add the mpi_sizeof of sc_MPI_UNSIGNED_LONG_LONG.

johannrudi/libsc,cburstedde/libsc,cburstedde/libsc,johannrudi/libsc,johannrudi/libsc,cburstedde/libsc,cburstedde/libsc,johannrudi/libsc,johannrudi/libsc,cburstedde/libsc