buildtools-tarball shouldn't be regenerated when MACHINE changes,
nor should variants for other SDKMACHINE be removed from the deploy
directory when SDKMACHINE changes.
Remove target architecture dependencies so that deploy artefacts
can overlap.
(From OE-Core rev: b7d1a310f6b880e92b124a78af3c948abaab4236)
Signed-off-by: Joshua Lock <joshua.g.lock@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>