fuse/impl_c: UNDO --auto-fsid option

fuse/impl_c: UNDO --auto-fsid option

rolling back:

Thu Sep 25 14:42:23 BST 2008  robk-tahoe@allmydata.com
  * fuse/impl_c: add --auto-fsid option

  this was inspired by reading the fuse docs and discovering the 'fsid' option
  to fuse_main, and was _intended_ to support a sort of 'stability' to the
  filesystem (specifically derived from the root-uri mounted, whether directly
  or via an alias) to support mac aliases across unmount/remount etc.

  some experimentation shows that that doesn't actually work, and that, at
  least for mac aliases in my testing, they're tied to path-to-mountpoint and
  not to the fsid - which seems to have no bearing.  perhaps the 'local' flag
  is causing weirdness therein.

  at any rate, I'm recording it simply for posterity, in case it turns out to
  be useful after all somewhere down the road.

    M ./contrib/fuse/impl_c/blackmatch.py +13