bb-determine-layers: improve error message for old python

Signed-off-by: Christopher Larson <kergoth@gmail.com>
kmod-native: fix build on old hosts

Resurrects O_CLOEXEC workaround.

Signed-off-by: Christopher Larson <kergoth@gmail.com>
dpkg-native: fix build on old hosts

Signed-off-by: Christopher Larson <kergoth@gmail.com>