When migrating old clients format (string array) to new format
(NFSClient objects), also fix any exports that have fsid=0 by
generating a new random fsid. This resolves exportfs errors like:
exportfs: /path fsid=0 requires fsid= for NFS export
The migration now checks if r.FSID == 0 and generates a new one
using system.GenerateRandomFSID() before updating the row.
darroyo
667576e5bd