Remove few warnings

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
autotools: Initial autotools build system

Ease the life of those that need to cross compile

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
NN_IPV4ONLY option added

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>