Add comment in GDBM informing to what param the 0 org corresponds to

Author: Girgias

ext/dba/dba_gdbm.c

@@ -46,7 +46,7 @@ DBA_OPEN_FUNC(gdbm)
 	if(gmode == -1)
 		return FAILURE; /* not possible */
 
-	dbf = gdbm_open(info->path, 0, gmode, filemode, NULL);
+	dbf = gdbm_open(info->path, /* int block_size */ 0, gmode, filemode, NULL);
 
 	if(dbf) {
 		info->dbf = pemalloc(sizeof(dba_gdbm_data), info->flags&DBA_PERSISTENT);