action: get rid of xkb_any_action

action: get rid of xkb_any_action

And use union xkb_action instead. We add xkb_private_action, which is
the same as xkb_any_action, but only used where the intention is clear.
This should take care of whatever sizing changes the action struct might
have.

Signed-off-by: Ran Benita <ran234@gmail.com>