We get the info for the underlying progression and invert it. For
progressions whose last bound was open (e.g., `until` loop), the
reversed version will have an open first bound and so the induction
variable must be incremented first.
Also unified the way of extracting HeaderInfo out of changed calls
(e.g., `indices.reversed()`), and fixed declaration parents in
ForLoopsLowering.
Mark Punzalan