Since we generally have lots of copies of the directories created using this tool, use
hardlinks where possible. This should save a little disk space and improve performance
slightly.
(From OE-Core rev: bfa11c028c2da093f7b4e6b7b1d611da90ae052f)
(From OE-Core rev: 8c5544c2311b080bb212efb7f6b804db63e125f5)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>