When the Wayland compositor vanishes, all applications connected will
receive a SIGPIPE as soon as they try to use wl_display_dispatch().
Do not use g_error() to terminate the applications when this occurs,
g_error() means an error in the application while here it's not truly
the case.
Use g_warning() and exit() instead.
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
https://bugzilla.gnome.org/show_bug.cgi?id=745289