Merge remote-tracking branch 'remotes/kraxel/tags/pull-vnc-3' into staging

Merge remote-tracking branch 'remotes/kraxel/tags/pull-vnc-3' into staging

misc minor vnc patches

# gpg: Signature made Mon 02 Jun 2014 15:31:53 BST using RSA key ID D3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <[email protected]>"
# gpg:                 aka "Gerd Hoffmann <[email protected]>"
# gpg:                 aka "Gerd Hoffmann (private) <[email protected]>"

* remotes/kraxel/tags/pull-vnc-3:
  vnc-enc-tight: Fix divide-by-zero in tight_detect_smooth_image{16,24,32}
  vnc: add trace events for key events
  vnc: refuse to set a password with VNC_AUTH_NONE

Signed-off-by: Peter Maydell <[email protected]>