Apps using randr to change the resolution when going fullscreen, in
combination with _NET_WM_STATE_FULLSCREEN to tell the window-manager (WM)
to make their window fullscreen, expect the WM to give the fullscreen window
the size of the emulated resolution as would happen when run under Xorg (*).

We need the WM to emulate this behavior for these apps to work correctly,
with Xwaylands resolution change emulation. For the WM to emulate this,
it needs to know about the emulated resolution for the Windows owning
client for each monitor.

This commit adds a _XWAYLAND_RANDR_EMU_MONITOR_RECTS property, which
contains 4 Cardinals (32 bit integers) per monitor with resolution
emulation info. Window-managers can use this to get the emulated
resolution for the client and size the window correctly.

*) Since under Xorg the resolution will actually be changed and after that
going fullscreen through NET_WM_STATE_FULLSCREEN will size the window to
be equal to the new resolution.

Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>
Acked-by: Michel Dänzer <mdaenzer@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>