The new command return dirty area to be used
by users that want spice to render localy or
into some framebuffer (sdl / vnc)
Signed-off-by: Izik Eidus <ieidus@redhat.com>
pixman_region32_t is an efficient well tested region implementation (its
the one used in X) that we already depend on via pixman and use in
some places. No need to have a custom region implementation.