This function will return different results based on the data available. If a city
database can be detected by the PECL module, it may return the country code,
region code, city name, area code, latitude, longitude and postal code of the visitor.
Alternatively, if only the country database can be detected, only the country code
will be returned.
The GeoIP PECL module will detect the following filenames:
- GeoIP.dat
- GeoIPCity.dat
- GeoIPISP.dat
- GeoIPOrg.dat
Note how GeoLiteCity.dat, the name for the GeoLite city database, is not detected
by the PECL module.