fix checkpointing for >4GB files

fix checkpointing for >4GB files

We incorrectly compute MPI_Offset for MPI IO for checkpointing using
SolutionTransfer using 32 bit indices, which means that files larger
than 4GB end up being corrupted.
This manifests in errors like

n error occurred in line <749> of file
<../source/distributed/tria_base.cc> in function
void dealii::parallel::DistributedTriangulationBase<dim,
spacedim>::load_attached_data(unsigned int, unsigned int, unsigned int,
const string&, unsigned int, unsigned int) [with int dim = 3; int
spacedim = 3; std::string = std::__cxx11::basic_string<char>]
The violated condition was:
(cell_rel.second == parallel::DistributedTriangulationBase<dim,
spacedim>::CELL_PERSIST)

part of #12752