Clarify a comment

storage/innobase/include/row0row.h

@@ -285,8 +285,8 @@ row_build_row_ref_fast(
 	const ulint*	map,	/*!< in: array of field numbers in rec
 				telling how ref should be built from
 				the fields of rec */
-	const rec_t*	rec,	/*!< in: record in the index; must be
-				preserved while ref is used, as we do
+	const rec_t*	rec,	/*!< in: secondary index record;
+				must be preserved while ref is used, as we do
 				not copy field values to heap */
 	const ulint*	offsets);/*!< in: array returned by rec_get_offsets() */
 /***************************************************************//**

storage/innobase/include/row0row.ic

 /*****************************************************************************
 
 Copyright (c) 1996, 2015, Oracle and/or its affiliates. All Rights Reserved.
+Copyright (c) 2017, MariaDB Corporation.
 
 This program is free software; you can redistribute it and/or modify it under
 the terms of the GNU General Public License as published by the Free Software
@@ -144,7 +145,7 @@ row_build_row_ref_fast(
 	const ulint*	map,	/*!< in: array of field numbers in rec
 				telling how ref should be built from
 				the fields of rec */
-	const rec_t*	rec,	/*!< in: record in the non-cluster index; 
+	const rec_t*	rec,	/*!< in: secondary index record;
 				must be preserved while ref is used, as we do
 				not copy field values to heap */
 	const ulint*	offsets)/*!< in: array returned by rec_get_offsets() */