Fix missed buttons in action.c if action_wait_for_release() was called
with no button pressed.
If e.g. two yesno screens directly follow each other the button release of the
first one was incorrectly accepted in the second one. The fix exposed another
problem in action.c if action_wait_for_release() is called when no button is
actually pressed. The next press was silently eaten.
This time re-introducing FS#12723 is avoided by leaving the offending hunk
out in yesno.c.
Change-Id: Icfe57375067f51f5c8177f3585cd47ceec9dcf0d