completion: complete --ita-invisible-in-index and --ita-visible-in-index
The options --ita-invisible-in-index and --ita-visible-in-index are
listed in diff-options.txt and so are included in the documentation of
commands which include this file (diff, diff-*, log, show, format-patch)
but they only make sense for diffs relating to the index. As such, add
them to '__git_diff_difftool_options' instead of
'__git_diff_common_options' since it makes more sense to add them there.
Signed-off-by: Philippe Blain <levraiphilippeblain@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>