[1.6.x] Fixed #21996 -- Used proper encoding for GeoIP content

Thanks Florent Messa for the report.
Backport of fb1e3435a4 from master.

django/contrib/gis/geoip/prototypes.py

@@ -22,6 +22,7 @@ class GeoIPRecord(Structure):
                 ('continent_code', c_char_p),
                 ]
 geoip_char_fields = [name for name, ctype in GeoIPRecord._fields_ if ctype is c_char_p]
+GEOIP_DEFAULT_ENCODING = 'iso-8859-1'
 geoip_encodings = { 0: 'iso-8859-1',
                     1: 'utf8',
                     }
@@ -92,7 +93,7 @@ def check_string(result, func, cargs):
         free(result)
     else:
         s = ''
-    return s.decode()
+    return s.decode(GEOIP_DEFAULT_ENCODING)
 
 GeoIP_database_info = lgeoip.GeoIP_database_info
 GeoIP_database_info.restype = geoip_char_p
@@ -102,7 +103,7 @@ GeoIP_database_info.errcheck = check_string
 def string_output(func):
     def _err_check(result, func, cargs):
         if result:
-            return result.decode()
+            return result.decode(GEOIP_DEFAULT_ENCODING)
         return result
     func.restype = c_char_p
     func.errcheck = _err_check

django/contrib/gis/geoip/tests.py

@@ -118,3 +118,5 @@ class GeoIPTest(unittest.TestCase):
         g = GeoIP()
         d = g.city("www.osnabrueck.de")
         self.assertEqual('Osnabrück', d['city'])
+        d = g.country('200.7.49.81')
+        self.assertEqual('Curaçao', d['country_name'])