XKB: Fix broken events

XKB: Fix broken events

XKB events all have exactly the same event number - 0 (from the XKB
event base).  Within this, they're all multiplexed by the xkbType field,
which comes immediately after the event type field, before the sequence
number.  Without this field, the events are pretty much useless, so add
it manually.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Uli Schlachter <psychon@znc.in>
Signed-off-by: Julien Danjou <julien@danjou.info>