Fix "make check-download", was broken by b0b6f82e
libgdmaps tests: check other databases for basic load (Issue #28)

Added new basic check for loading arbitrary GeoIP database
  pathnames, listed in the env var GDMAPS_GEOIP_TEST_LOAD.
  The files are simply loaded and queried while ignoring results,
  in hopes of catching stupid crashes against newer/different
  data than the fixed test set, when the tester has such data
  available.  If left unspecified, the test script will attempt
  defaulting to /usr/share/GeoIP/Geo*.dat if any such pathnames
  exist on the test host.

Example:
  GDMAPS_GEOIP_TEST_LOAD="/somedir/GeoIPTestDatav[46].dat" make check