xwayland: Include xwayland-window.h from xwayland-glamor-eglstream.c
Fixes build failure. Closes: xorg/xserver#954 Fixes: 89e32d00 "xwayland: Move Xwayland windows to its own sources" Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net> Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>