Log Message:
Update to 1.3.8.

Changes:
* Made code thread safe by replacing gethostbyname with gethostbyname_r
* Added GeoIP_country_code_by_ipnum and GeoIP_id_by_ipnum to use
  existing ulong IP Address in numeric form instead of having to
  convert it to string (Boris Hajduk)
* Updated geoipupdate to report invalid userID and productID errors
* Added support for GEOIP_INDEX_CACHE - which just caches
  the most frequently access index portion of the database, resulting
  in faster lookups than GEOIP_STANDARD, but less memory usage than
  GEOIP_MEMORY_CACHE (Frank Mather)
* Made GEOIP_CHECK_CACHE work with GEOIP_STANDARD mode - reloads filehandle
  in case file changes.
* Made GeoIP City code thread safe
* Fixed bug with geoipupdate reading in product ids
* Added support for GeoIP Netspeed geoipupdate
* Fix memleak in lookupaddress (Ludwig Nussel/SUSE)
* Add prototype for _full_path_to to make 64bit clean (Ludwig Nussel/SUSE)