Merge remote-tracking branch 'remotes/kraxel/tags/pull-vnc-20160712-1' into staging

Merge remote-tracking branch 'remotes/kraxel/tags/pull-vnc-20160712-1' into staging

vnc: misc bugfixes.

# gpg: Signature made Tue 12 Jul 2016 08:22:40 BST
# gpg:                using RSA key 0x4CB6D8EED3E87138
# gpg: Good signature from "Gerd Hoffmann (work) <kraxel@redhat.com>"
# gpg:                 aka "Gerd Hoffmann <gerd@kraxel.org>"
# gpg:                 aka "Gerd Hoffmann (private) <kraxel@gmail.com>"
# Primary key fingerprint: A032 8CFF B93A 17A7 9901  FE7D 4CB6 D8EE D3E8 7138

* remotes/kraxel/tags/pull-vnc-20160712-1:
  ui: avoid crash if vnc client disconnects with writes pending
  vnc-enc-tight: use thread local storage for palette
  vnc: fix incorrect checking condition when updating client

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>