hammer2 - Misc cluster protocol work

hammer2 - Misc cluster protocol work

* Adjust debugging a bit so hammer2 -d bumps DMsgDebugOpt to sucessively
  higher values.

* mount_hammer2 now connects the hammer2 service daemon to the mount
  via localhost instead of via 0 (0 does not bind to localhost if the
  machine has an IP address).  Allows differentiation between remote
  connections and local connections.

* Begin splitting the dmsg iocom stuff off from vfsops.c in the hammer2 VFS
  and test.

* Issue SPANs relative to state0 rather than the LNK_CONN state in the hammer2
  VFS, to match how SPANs are implemented in the service demon.

* Recognize remote HAMMER2 filesystem SPANs (but don't do anything with them
  yet).

* Fix a brace bug in hammer2_bulkscan.c (from swildner).