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/m4/version-etc.m4

@@ -0,0 +1,33 @@
+# version-etc.m4 serial 1
+# Copyright (C) 2009-2017 Free Software Foundation, Inc.
+# This file is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+dnl $1 - configure flag and define name
+dnl $2 - human readable description
+m4_define([gl_VERSION_ETC_FLAG],
+[dnl
+  AC_ARG_WITH([$1], [AS_HELP_STRING([--with-$1], [$2])],
+    [dnl
+      case $withval in
+        yes|no) ;;
+        *) AC_DEFINE_UNQUOTED(AS_TR_CPP([PACKAGE_$1]), ["$withval"], [$2]) ;;
+      esac
+    ])
+])
+
+AC_DEFUN([gl_VERSION_ETC],
+[dnl
+  gl_VERSION_ETC_FLAG([packager],
+                      [String identifying the packager of this software])
+  gl_VERSION_ETC_FLAG([packager-version],
+                      [Packager-specific version information])
+  gl_VERSION_ETC_FLAG([packager-bug-reports],
+                      [Packager info for bug reports (URL/e-mail/...)])
+  if test "X$with_packager" = "X" && \
+     test "X$with_packager_version$with_packager_bug_reports" != "X"
+  then
+    AC_MSG_ERROR([The --with-packager-{bug-reports,version} options require --with-packager])
+  fi
+])