Fix compilation when we don't HAVE_GEOIP.

We really need a buildbot or Petri-Dish which doesn't have GeoIP because
this problem keeps popping up.

Bug: 10480
Change-Id: Iccba50dfcafd2dbacb315b9416324de4114be220
Reviewed-on: https://code.wireshark.org/review/4171
Reviewed-by: Jeff Morriss <jeff.morriss.ws@gmail.com>