Autotest: don't leak a socket every call to QtNetworkSettings::hasIPv6

Change-Id: I87e31945052233cee17460ee6f59c02ec416b27b
Reviewed-by: Richard J. Moore <rich@kde.org>

tests/auto/network-settings.h

@@ -116,6 +116,7 @@ public:
                 return false;
             }
         }
+        ::close(s);
 #endif
         return true;
     }