Work around Wayland issue
    
    For some reason the binary doesn't work under Wayland. I haven't yet
    figured out the root cause of the issue, but according to the interwebz
    running chessx with QT_QPA_PLATFORM=xcb works around it (by forcing Qt
    to use X, therefore XWayland, instead of the native Wayland
    integration).
    
    Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>