Function mpi::ffi::PMPI_Neighbor_allgather

pub unsafe extern fn PMPI_Neighbor_allgather(sendbuf: *const c_void,
                                             sendcount: c_int,
                                             sendtype: MPI_Datatype,
                                             recvbuf: *mut c_void,
                                             recvcount: c_int,
                                             recvtype: MPI_Datatype,
                                             comm: MPI_Comm)
                                             -> c_int