hush: support "for if in do done then; do echo $if; done" case

hush: support "for if in do done then; do echo $if; done" case

function                                             old     new   delta
done_pipe                                             83      95     +12
parse_stream                                        1758    1764      +6
done_word                                            674     647     -27
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(add/remove: 0/0 grow/shrink: 2/1 up/down: 18/-27)             Total: -9 bytes