Load geoip and geoip6 files during the unit tests

We don't run any tests on the contents of the geoip and geoip6 files.

We should write a test that loads the files, and fails if they fail to parse, are empty, or have an unexpected number of entries. (+-25% of the current number of entries?)

We might want a #define that skips the test, so that people can build and test without geoip. (We might eventually want geoip to be an optional module, but that's out of scope.)

Maybe karsten can tell us how much the number of entries in the geoip files varies?