dhclient up to 4 seconds faster

[Marc Herbert <Marc Herbert gmail com>]

Tired of waiting for dhclient? I was, I traced, I won.

  https://bugzilla.redhat.com/show_bug.cgi?id=587070

People repeatedly testing NetworkManager should especially like this.

It's just a dead-simple one-line change, but it requires
recompilation. So familiarity with yumdownloader --source + rpmbuild
(or apt-get source,...) is recommended.