sockets: switch vnc to new code, support vnc port auto-allocation (Gerd Hoffman)

sockets: switch vnc to new code, support vnc port auto-allocation (Gerd Hoffman)

This patch switches the vnc code ofer to the new socket helper
functions.

It adds support IPv6 support and for automatically allocating an unused
vnc display port.  The latter is handled ising a to= option, specifying
the upper limit for the display number to try.  Scanning is started at
the display number given in the display specification, i.e. this command
line:

    -vnc localhost:7,to=11

will try displays 7 to 11 (inclusive).

There are also new "ipv4" and "ipv6" options to make qemu try only
the specified internet protocol version.

The display actually allocated can be queried using the "info vnc"
monitor command.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5696 c046a42c-6fe2-441c-8c8c-71466251a162