add-patch: let options a and d roll over like y and n

add-patch: let options a and d roll over like y and n

Options a and d stage and unstage all undecided hunks towards the bottom
of the array of hunks, respectively, and then roll over to the very
first hunk.  The first part is similar to y and n if the current hunk is
the last one in the array, but they roll over to the next undecided
hunk if there is any.  That's more useful; do it for a and d as well.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>