Fixed #6801: Delay sending of resolution change

Fixed #6801: Delay sending of resolution change

Changed the logic of the disp channel to wait for 800ms after a
ConfigureNotify before sending the new resolution.
The problem fixed with this patch is the following:
1.  Resize the window with the mouse
2.  ConfigureNotify triggers a resize notification
3.  The server resizes to the desired resolution
3a. More ConfigureNotify events are generated
4.  The local window resize to the new resolution triggers another
    ConfigureNotify

a. Depending on the timing (sending is already rate limited) the
   events from 3a and 4 will make the size of the window jump
b. Very fast resizing will pick a random resolution from the
   sequence of ConfigureNotify events as the final resolution

(cherry picked from commit d3ed42a7994975098973c5f29f1ab98f7bdac2bf)