match_pathspec: match pathspec "foo/" against directory "foo"

match_pathspec: match pathspec "foo/" against directory "foo"

Currently we do support matching pathspec "foo/" against directory
"foo". That is because match_pathspec() has no way to tell "foo" is a
directory and matching "foo/" against _file_ "foo" is wrong.

The callers can now tell match_pathspec if "foo" is a directory, we
could make an exception for this case. Code is not executed though
because no callers pass the flag yet.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>