Similar to rpm, use copies of the ipk/deb directories for rootfs construction.
This means the image creation code can no longer "see" recipes wich aren't in its
dependency chain which is good for a variety of reasons including determinism,
incompatible recipe (e.g. systemd/sysvinit) package conflicts and locking
performance.
(From OE-Core rev: c7c5f4065c102fde4e11d138fb0b6e25bffe0379)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>