Add a post-index-change hook that is invoked after the index is written in
do_write_locked_index().
This hook is meant primarily for notification, and cannot affect
the outcome of git commands that trigger the index write.
The hook is passed a flag to indicate whether the working directory was
updated or not and a flag indicating if a skip-worktree bit could have
changed. These flags enable the hook to optimize its response to the
index change notification.
Signed-off-by: Ben Peart <benpeart@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
