libweston-desktop: don't crash when getting the pid for X clients

X client's don't have a wl_client associated with their
weston_desktop_client, so make sure to not use it.

Signed-off-by: Giulio Camuffo <giuliocamuffo@gmail.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
2 files changed