Function mpi::ffi::MPI_Grequest_start

pub unsafe extern fn MPI_Grequest_start(query_fn: MPI_Grequest_query_function,
                                        free_fn: MPI_Grequest_free_function,
                                        cancel_fn: MPI_Grequest_cancel_function,
                                        extra_state: *mut c_void,
                                        request: *mut MPI_Request)
                                        -> c_int