xwayland: Delay cursor visibility update

Xwayland won't emulate XWarpPointer requests if the cursor is visible,
this is to avoid having the cursor jumping on screen and preventing
random X11 clients from controlling the pointer in Wayland, while
allowing games which use that mechanism with a hidden cursor to work in

There are, however, games which tend to do it in the wrong order, i.e.
show the cursor before moving the pointer, and because Xwayland will not
allow an X11 client to move the pointer while the cursor is visible, the
requests will fail.

Add a workaround for such X11 clients, when the cursor is being shown,
keep it invisible until the cursor is actually moved. This way, X11
clients which show their cursor just before moving it would still have a
chance to succeed.

v2: Add a timeout to show the cursor for well behaved clients.
v3: Some cleanup (Michel)
v4: Do not cancel cursor delay when updating the cursor to avoid
    delaying cursor visibility indefinitely if the client keeps
    settings different cursors (Michel)

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
Tested-by: Jaap Buurman jaapbuurman@gmail.com
Reviewed-by: Michel Dänzer <mdaenzer@redhat.com>
Closes: xorg/xserver#734
4 jobs for xwayland-warp-newly-visible-cursor in 5 minutes and 24 seconds (queued for 1 second)