configure: Fail if libnl3 dependency is not found

The conditionals are not used anywhere and we have a hard dependency on
libnl3 so fail if we do not detect it during configure.

Signed-off-by: Stefan Schmidt <s.schmidt@samsung.com>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
build: add header files to SOURCES

We need to specify them here or they will not end up in the tarball and thus
distcheck would fail.

Signed-off-by: Stefan Schmidt <s.schmidt@samsung.com>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>
configure: do not use check-news for now

We do not use a NEWS file right now and without it distcheck will fail
with this option. We can bring it back when we are going to use a NEWS
file for keeping track.

Signed-off-by: Stefan Schmidt <s.schmidt@samsung.com>
Signed-off-by: Alexander Aring <alex.aring@gmail.com>