sstate: Add packagedata to list of tasks not to recurse

sstate: Add packagedata to list of tasks not to recurse

If we "bitbake X -c packagedata" and the packagedata comes from sstate, we
don't need any of the tasks dependencies. This is similar to the
populate_lic case, we only care about the end result.

Therefore short circuit the dependencies so packagedata doesn't pull in
any other dependencies.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>