Say goodbye to libdhcp in anaconda.

This enormous patch for anaconda removes our use of libdhcp (which also
means libdhcp4client and libdhcp6client) in favor of spawning the client
daemons if users want DHCP or DHCPv6.  In addition, iface.c in libisys has
been expanded to do static network configuration via libnl, which replaces
the pump-like code that was in libdhcp.  A number of utility functions
have been put in iface.c for use in libisys as well as loader.

Here is a list of the major changes in this code:

1) A new interface configuration API in libisys.  The API functions are
   listed in iface.h.  These functions give us information about the current
   state of the interface, configure an interface (manually, by DHCP, by
   DHCPv6, or by neighbor discovery), bring an interface up or down, clear
   an interface's configuration, and other functions.  iface.c uses libnl
   and the sockets API to do its work.

2) Remove all use of pumpIntfInfo and networkDeviceConfig.  All interface
   configuration is now in type 'iface_t'.  Loader made it difficult to
   trace problems.  No more things like dev->dev.device to get 'eth0'.

3) No more storing information as an ip_addr_t.  Since libdhcp is gone, so
   is this utility type for storing either an in_addr or in6_addr.  We just
   store in_addr or in6_addr now.  For values that could be either family,
   we store the human-readable representation as a char * mostly because
   that's the form we'll need it in most often and converting to an in_addr
   or in6_addr on the fly is cheap.

4) Adding /sbin/dhclient and /sbin/dhcp6c to the stage 1 image.  dhclient
   also requires the dhclient-script, so that's in the image as well,
   including the tools it needs.

5) As much removal of duplicate information as possible.  More patches for
   this later.

6) No longer storing the IPv4 network address.  We don't need it anymore
   except to calculate our broadcast address, so it's done there and then
   thrown out.

7) Error checking improvements in loader and libisys code.

8) Reduction of loader2/net.c code.  There was a lot of duplication.  With
   the new iface API, a lot of things in loader's net.c code were able to
   be removed.  For example, there is no longer the cfg vs. newCfg in many
   of the functions (or iface vs. newiface with the new code).

This patch focuses on the backend network configuration code.  The next
patch will be to rework user interface code with the following major
changes:

    - Collecting the IPv6 default gateway from the user.
    - Collecting any needed NetworkManager settings from the user, as
      well as just improving our interaction with NM.
    - Collecting per-interface resolv.conf information (NM uses this if
      it finds it).
    - And more probably.

-- 
David Cantrell <dcantrell@redhat.com>