Bugfix: faulty assert() in ntree v4 lookup code

The assert was probably copied from lookup_v6 to lookup_v4, but
  the IP address in the v4 version is not a pointer, it's a 32-bit
  raw value, and thus the assert fails if one does a lookup on
  the address 0.0.0.0.

Found by Mark Bergsma testing a variant of the code that was copied
  to the varnish module libvmod_netmapper for WMF use.

The assert fail can be triggered by a real packet which contains an
  edns-client-subnet address of 0.0.0.0 and a non-zero source mask
  which queries a name served by plugin_geoip, if the daemon was
  built in debug mode.  I haven't been able to produce any failure
  in non-debug builds, though, so I suspect that gcc isn't doing
  anything dangerous with the related __builtin_unreachable()
  optimization in non-debug builds, seeing as it's not a pointer
  check and there are no obvious math optimizations, either.
Testsuite now checks EDNS comparisons more thoroughly

Previously, the testsuite wasn't really comparing the deeper
  option data in EDNS OPT RRs, such as edns-client-subnet info.