mpi_f08: Fix param name and string length for MPI_GET_LIBRARY_VERSION

Junchao Zhang pointed out to me that we had the wrong parameter name
and string length specification for the "version" parameter.  This
matters because Fortran allows passing by parameter name
(vs. parameter ordering).  Specifically, we had the interface as:

{{{
subroutine MPI_Get_library_version_f08(name,resultlen,ierror)
   character(len=MPI_MAX_PROCESSOR_NAME), intent(out) :: name
...etc.
}}}

but it should be:

{{{
subroutine MPI_Get_library_version_f08(version,resultlen,ierror)
   character(len=MPI_MAX_LIBRARY_VERSION_STRING), intent(out) :: version
...etc.
}}}

Thankfully, MPI_MAX_PROCESSOR_NAME and MPI_MAX_LIBRARY_VERSION_STRING
are both 255 in OMPI, so there's no ABI issue caused by changing the
length from MMPN --> MMLVS.

The ABI is also unaffected by the parameter name change: if you
compile/link an MPI application calling MPI_GET_LIBRARY_VERSION with
1.8, it'll still run-time link with this change.

However, if an MPI program compiled using parameter name passing with
the old/incorrect parameter name ("name"), it won't be able to compile
with the new/correct parameter name ("version").  But this will only
happen for an incorrect MPI application (because the MPI-3 mandated
parameter name is "version", not "name"), so they deserve what they
get.

cmr=v1.8.1:reviewer=dgoodell