api-directory-listing.txt: update to match code
api-directory-listing.txt: update to match code

7c4c97c0ac turned the flags in struct dir_struct into a single bitfield
variable, but forgot to update this document.

Signed-off-by: Adam Spiers <46f1a0bd5592a2f9244ca321b129902a06b53e03@adamspiers.org>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git