The GitHub actions pipeline is not interrupted for unset symbols due to
OpenWrt not failing in all cases of unset symbols.
Adda patch to consistently fail for unset symbols.
Ref #2701 (build process is waiting for user input)
Signed-off-by: David Bauer <mail@david-bauer.net>
Signed-off-by: David Bauer <mail@david-bauer.net>
