r5520: fix last remaining dfs issues with smbclient.

r5520: fix last remaining dfs issues with smbclient.

* all the unix extension commands should work
* send the correct TRANS2_FINDFIRST format to 2k to
  get a listing from a msdfs root share (tested against
  smbd as well).
* mkdir, rmdir, etc... all seem ok.

I'm sure bugs will pop up so keep testing.

Last thing I plan on doing is to clean up the horrible
mess with connection management in smbclient and global
variables (so i can move the cli_cm_xx() routines to a
separate file).
(This used to be commit 53d6a5f9d16aef4afc60b4b37b296b256da00dfd)