populate_sdk_base/images: Drop use of 'meta' class and hence do_build dependencies
The 'meta' is old and not very useful. It empties PACKAGES and creates
recursive do_build dependencies.
We shouldn't need such recursive build dependencies any more so simplify the code.
This does cause behaviour changes as some dependencies are no longer built.
It did show up issues with qemu-helper-native handling for example but those
issues look like real races and the underlying dependency chains were not correct.
'bitbake XXX --runall build' would give the previous behaviour.
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
