We still have problems where deploying SDKMACHINE=i686 can cause removal
of SDKMACHINE=x86_64 artefacts.
The reason is that x86_64 is a BUILD_ARCH as well as an SDK_ARCH and
the manifest namespaces overlap. To fix this, set PACKAGE_ARCH and
the stamp-extra-into to include SDK_OS. SDK_OS may not be entirely correct
but it is what sstate.bbclass uses for nativesdk and fixing that is
a separate issue.
This is confirmed to resolve artefact problems on the AB which have been
delaying a new uninative release.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>