fcoll/vulcan: fix memory leak

we didn't correctly free the fh->f_aggr_list array in the vulcan file_write_all file.
Thanks @andymwood for reporting the issue and @ggouaillardet for identifying the cause for the leak.

Fixes Issue #12677 (at least partially)

Signed-off-by: Edgar Gabriel <[email protected]>
(cherry picked from commit 3fde6af)

Author: edgargabriel

ompi/mca/fcoll/vulcan/fcoll_vulcan_file_write_all.c

@@ -729,8 +729,10 @@ exit :
     }
     free(broken_iov_arrays);
     free(fh->f_procs_in_group);
+    free(fh->f_aggr_list);
     fh->f_procs_in_group=NULL;
     fh->f_procs_per_group=0;
+    fh->f_aggr_list=NULL;
     free(result_counts);
     free(reqs);