contrib/rpm: Count all predecessors in revision number

After an octopus merge, the first parent is not guarranteed to contain the
commit the reference pointed to previously.
build: ensure rl_echo_signal_char() exists in the readline library
device: Don't consider device with only LL address configured

LXC domains are given a veth interface that's up and has a LL address
upon their creation.
device: don't assume connection for veth interfaces

They're supposed to behave as Ethernet. Otherwise the LXC domains won't
be able to use their configured connections with the device.
Merge remote-tracking branches 'lr/lr-unmanaged-slaves', 'lr/lr-ipv6-tokens', 'lr/lr-ap', 'lr/lr-rdisc-mtu', 'lr/lr-rpm-build' and 'lr/lr-lxc' into integration