Xwayland uses the command line option “-listen” to pass file descriptors
from the Wayland compositor.
That breaks the traditional, documented behavior of the “-listen”
command line option which is to enable a transport type.
Checks if the given option starts with a digit, otherwise treat it as a
regular transport type.
Closes: https://gitlab.freedesktop.org/xorg/xserver/issues/817
Suggested-by: Rodrigo Exterckötter Tjäder
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>