Include gdk/gdkwayland.h anytime GDK_WINDOWING_WAYLAND is defined.
Include gdk/gdkwayland.h anytime GDK_WINDOWING_WAYLAND is defined.

A specific GTK version check is not appropriate for this particular include.
This fixes compilation on Debian Jessie.

Signed-off-by: Jeremy White <dd63f6c315752c6a657e194d3b984bc3cb719f6d@codeweavers.com>

SPICE/spice-gtk,SPICE/spice-gtk,SPICE/spice-gtk,SPICE/spice-gtk,fgouget/spice-gtk,flexVDI/spice-gtk,fgouget/spice-gtk,flexVDI/spice-gtk,fgouget/spice-gtk