The configuration preservation mechanism fails to keep items was are unset
as unset. For busybox this causes issues when building with custom
settings in the SDK. Therefore preserve busybox unset settings.
In addition we preserve non-package selection unset settings because
they may be important for making sure we compile and identical
package for packages that are recompiled in the SDK.
Now that SDK not longer ships .config this becomes relevant for
any use of the SDK.
Signed-off-by: Daniel Dickinson <lede@daniel.thecshore.com>
Commit d79f8909c1 introduced CONFIG_ALL,
CONFIG_ALL_KMODS and CONFIG_ALL_NONSHARED as menuconfig choices to the SDK,
therefor we can drop the hardcoded CONFIG_ALL symbol declaration now.
Signed-off-by: Jo-Philipp Wich <jo@mein.io>
