Normalize signal & slot signatures in connection

Profiling shows Qt Creator spends 2% of its load time normalizing

Change-Id: I48937197efac2ea93571f616ed4e94551540bd5d
Reviewed-by: Pier Luigi Fiorini <pierluigi.fiorini@gmail.com>
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
init mTouchDevice to null

Since QWaylandInputDevice::seat_capabilities checks the pointer before
creating this object, it must be initially null so that the device
will be registered.

Change-Id: Ia15b407b1636eab41c04f30bb631306095e5aefb
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>
Fix the client behavior when showing or hiding a surface

Reduce the chances of seeing a bad frame.

Change-Id: Idac3450d92210fc5fc33cb68862b089964c9a8ce
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>
Fix build break in linux

Fixes build break when built on linux with wayland libs installed
via pkg manager.

Change-Id: I17be64e702d07e817a2e34e76ddbe8dde064f3d2
Reviewed-by: Andrew Knight <andrew.knight@digia.com>
Improve the frame callbacks handling

Improve the way wl_surface's frame callbacks are handled. The sooner
they are sent the better is for the clients, as they have more time to
render the next frame, but reducing the time for the compositor to
render its frame. The best compromise is probably to send them out
after the compositor has issued its GL calls but before calling
eglSwapBuffers(), and before the GPU actually draws anything.
Rename the function to send the callbacks to only reflect its purpose,
leaving the compositors free to choose when they want to send them.

Change-Id: Ifcdfcad9e54b4d07d5c087898123ac724395a194
Reviewed-by: Jørgen Lind <jorgen.lind@digia.com>