[mpich romio ad0e435] romio fix when used in -Wpedantic build environments

> Pulled in from mpich romio, branch "main".
> Their commit message is below.
>
> This is part of a batch of commits from the
> following set of PRs:
>  *  pmodels/mpich#4943
>     -- darray fix which contains a flatten fix
>         73a3eba
>         c4b5762
>  *  pmodels/mpich#4995
>     -- write strided fix
>         bbb5210
>  *  pmodels/mpich#5100
>     -- build fix for -Wpedantic
>         ad0e435
>  *  pmodels/mpich#5099
>     -- build fix, they had let file-system=...gpfs bit rot
>         e1d42af
>         313289a
>         83bbb82
>  *  pmodels/mpich#5150
>     -- build fix, configure-related _GNU_SOURCE
>         a712b56
>         5a036e7
>  *  pmodels/mpich#5184
>     -- build fix, continuation of _GNU_SOURCE fix
>         d97c4ee

typecasting a (void*) due to compiler complaint when -Wpedantic is used

Signed-off-by: Mark Allen <markalle@us.ibm.com>

Author: markalle

3rd-party/romio341/adio/ad_gpfs/ad_gpfs_wrcoll.c

@@ -1541,7 +1541,7 @@ static void ADIOI_W_Exchange_data_alltoallv(ADIO_File fd, const void *buf, char
         for (i = 0; i < nprocs; i++) {
             if (send_size[i]) {
                 sbuf_ptr = all_send_buf + sdispls[i];
-                memcpy(sbuf_ptr, buf + buf_idx[i], send_size[i]);
+                memcpy(sbuf_ptr, (char *) buf + buf_idx[i], send_size[i]);
                 buf_idx[i] += send_size[i];
             }
         }