Update Windows instructions for building with GeoIP support
The GeoIP section of win32utils/build.txt is outdated and needs to be revised to reflect the current state of things:
Step 5: Download and build GeoIP
Geographic ("geoip") ACLs require libGeoIP. If you wish to build BIND 9
without support for this feature, skip to step 6.
The libGeoIP source code is available from:
https://github.com/maxmind/geoip-api-c/releases.
As of this writing, the current version of libGeoIP is 1.6.0. There
is a known bug in this and all prior versions which prevents it from
building a suitable DLL with thread support on Windows. You can apply
the patch file bind9/win32utils/GeoIP.diff to address the problem.
This patch has been submitted upstream, and will be included in
future versions of libGeoIP.