libnl: drop libnl-1 dependency

El6.6 is out. Since the next release of vdsm will not support
earlier releases than that, we can finally depend exclusively on
libnl3 and remove libnl1 glue code.

The next step should be to leverage the extra things that libnl3
gives us that we could not use up until now, e.g., routes support
for source routing.

Change-Id: I3a6fa58a79030d4d56bfec59b2c459830aa5e317
Signed-off-by: Antoni S. Puimedon <asegurap@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/34677
Reviewed-by: Petr Horáček <phoracek@redhat.com>
Tested-by: Petr Horáček <phoracek@redhat.com>
Reviewed-by: Dan Kenigsberg <danken@redhat.com>