#916297 gtk2 ui: add exitstatus to on_child_exited
In VTE 2.91, child_exited was changed to give the child's exit status, compare:
https://valadoc.org/vte-2.90/Vte.Terminal.child_exited.html
https://valadoc.org/vte-2.91/Vte.Terminal.child_exited.html
Reportbug uses vte 2.91 now and needs to follow this change.