Fix numpad handling in QEMU's VNC server. The keymaps that we have include

Fix numpad handling in QEMU's VNC server.  The keymaps that we have include
information on which keys change depending upon the numlock setting, but
this isn't being used.  By forcing numlock on and off as necessary, when
receiving these keysyms through the VNC connection, we ensure that the
server's numlock status is the same as the client's.

Signed-off-by: Ewan Mellor <ewan@xensource.com>