D7: editor multi-cursor support

Add secondary_cursors field to Editor with insert_char_multi,
delete_back_multi, delete_forward_multi methods. Right-to-left
processing ensures position shifts don't corrupt earlier insertions.

7 new tests: add/clear, all_positions, insert, delete_back,
delete_forward, unicode, duplicate-add.

local/recipes/tools/diffutils/source/lib/mkstemp.c

@@ -0,0 +1,50 @@
+/* Copyright (C) 1998-1999, 2001, 2005-2007, 2009-2017 Free Software
+   Foundation, Inc.
+   This file is derived from the one in the GNU C Library.
+
+   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 Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#if !_LIBC
+# include <config.h>
+#endif
+
+#include <stdlib.h>
+
+#if !_LIBC
+# include "tempname.h"
+# define __gen_tempname gen_tempname
+# ifndef __GT_FILE
+#  define __GT_FILE GT_FILE
+# endif
+#endif
+
+#include <stdio.h>
+
+#ifndef __GT_FILE
+# define __GT_FILE 0
+#endif
+
+/* Generate a unique temporary file name from XTEMPLATE.
+   The last six characters of XTEMPLATE must be "XXXXXX";
+   they are replaced with a string that makes the file name unique.
+   Then open the file and return a fd.
+
+   If you are creating temporary files which will later be removed,
+   consider using the clean-temp module, which avoids several pitfalls
+   of using mkstemp directly. */
+int
+mkstemp (char *xtemplate)
+{
+  return __gen_tempname (xtemplate, 0, 0, __GT_FILE);
+}