Some compositors might not offer wl_seat 4 resulting in GTK+ clients not
working on that compositor.
wl_seat 4 introduces keyboard repeat information, but when that information
is missing it is retrieved from settings, hence there's no reason to
require wl_seat 4.
This patch was tested against QtCompositor (5.5, dev branch)
and Weston 1.6.1.
Reviewed-by: Daniel Stone <daniels@collabora.com>
https://bugzilla.gnome.org/show_bug.cgi?id=744172