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/sys_ioctl_h.m4

@@ -0,0 +1,64 @@
+# sys_ioctl_h.m4 serial 10
+dnl Copyright (C) 2008-2017 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+dnl Written by Bruno Haible.
+
+AC_DEFUN([gl_SYS_IOCTL_H],
+[
+  dnl Use AC_REQUIRE here, so that the default behavior below is expanded
+  dnl once only, before all statements that occur in other macros.
+  AC_REQUIRE([gl_SYS_IOCTL_H_DEFAULTS])
+
+  AC_CHECK_HEADERS_ONCE([sys/ioctl.h])
+  if test $ac_cv_header_sys_ioctl_h = yes; then
+    HAVE_SYS_IOCTL_H=1
+    dnl Test whether <sys/ioctl.h> declares ioctl(), or whether some other
+    dnl header file, such as <unistd.h> or <stropts.h>, is needed for that.
+    AC_CACHE_CHECK([whether <sys/ioctl.h> declares ioctl],
+      [gl_cv_decl_ioctl_in_sys_ioctl_h],
+      [dnl We cannot use AC_CHECK_DECL because it produces its own messages.
+       AC_COMPILE_IFELSE(
+         [AC_LANG_PROGRAM(
+            [AC_INCLUDES_DEFAULT([#include <sys/ioctl.h>])],
+            [(void) ioctl;])],
+         [gl_cv_decl_ioctl_in_sys_ioctl_h=yes],
+         [gl_cv_decl_ioctl_in_sys_ioctl_h=no])
+      ])
+  else
+    HAVE_SYS_IOCTL_H=0
+  fi
+  AC_SUBST([HAVE_SYS_IOCTL_H])
+  dnl <sys/ioctl.h> is always overridden, because of GNULIB_POSIXCHECK.
+  gl_CHECK_NEXT_HEADERS([sys/ioctl.h])
+
+  dnl Check for declarations of anything we want to poison if the
+  dnl corresponding gnulib module is not in use.
+  gl_WARN_ON_USE_PREPARE([[#include <sys/ioctl.h>
+/* Some platforms declare ioctl in the wrong header.  */
+#if !(defined __GLIBC__ && !defined __UCLIBC__)
+# include <unistd.h>
+#endif
+    ]], [ioctl])
+])
+
+AC_DEFUN([gl_SYS_IOCTL_MODULE_INDICATOR],
+[
+  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
+  AC_REQUIRE([gl_SYS_IOCTL_H_DEFAULTS])
+  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
+  dnl Define it also as a C macro, for the benefit of the unit tests.
+  gl_MODULE_INDICATOR_FOR_TESTS([$1])
+])
+
+AC_DEFUN([gl_SYS_IOCTL_H_DEFAULTS],
+[
+  GNULIB_IOCTL=0;         AC_SUBST([GNULIB_IOCTL])
+  dnl Assume proper GNU behavior unless another module says otherwise.
+  SYS_IOCTL_H_HAVE_WINSOCK2_H=0; AC_SUBST([SYS_IOCTL_H_HAVE_WINSOCK2_H])
+  SYS_IOCTL_H_HAVE_WINSOCK2_H_AND_USE_SOCKETS=0;
+                        AC_SUBST([SYS_IOCTL_H_HAVE_WINSOCK2_H_AND_USE_SOCKETS])
+  REPLACE_IOCTL=0;      AC_SUBST([REPLACE_IOCTL])
+])