(svn r20450) -Fix: same the airport tile ID mapping as well

src/saveload/airport_sl.cpp

@@ -24,6 +24,17 @@ static void Load_APID()
 	Load_NewGRFMapping(_airport_mngr);
 }
 
+static void Save_ATID()
+{
+	Save_NewGRFMapping(_airporttile_mngr);
+}
+
+static void Load_ATID()
+{
+	Load_NewGRFMapping(_airporttile_mngr);
+}
+
 extern const ChunkHandler _airport_chunk_handlers[] = {
+	{ 'ATID', Save_ATID, Load_ATID, NULL, NULL, CH_ARRAY },
 	{ 'APID', Save_APID, Load_APID, NULL, NULL, CH_ARRAY | CH_LAST },
 };