Flyspell relies on the sorting order of overlays from 'overlays-in'
that returned the overlays sorted by decreased 'overlay-start'.
But after the recent merge of the noverlay branch, the order was reversed.
So need to change the order back to the expected by Flyspell.
* lisp/textmodes/flyspell.el (flyspell-auto-correct-previous-word):
Sort overlays returned from 'overlays-in' descending by 'overlay-start'.