Some socket settings used to be retrieved via the listener and the
bind_conf. Now instead we use the receiver and its settings whenever
appropriate. This will simplify the removal of the dependency on the
listener.
The netns is common to all listeners/receivers and is used to bind the
listening socket so it must be in the receiver settings and not in the
listener. This removes some yet another set of unnecessary loops.
Let's continue the cleanup and get rid of all sample fetch functions
from proto_tcp.c. They're now moved to tcp_sample.c, just as was done
for ssl before 2.2 release. Nothing has changed beyond this.
