Function mpi::ffi::MPI_Iallreduce

pub unsafe extern fn MPI_Iallreduce(sendbuf: *const c_void,
                                    recvbuf: *mut c_void,
                                    count: c_int,
                                    datatype: MPI_Datatype,
                                    op: MPI_Op,
                                    comm: MPI_Comm,
                                    request: *mut MPI_Request)
                                    -> c_int