getopt needs extensions

[Bruno Haible]

According to POSIX, <unistd.h> should declare optarg, optind, etc. But on
Solaris, the system header does this only if __EXTENSIONS__ is defined.
This makes its use in gnulib automatic:


2009-08-12  Bruno Haible  <address@hidden>

        Ensure that optarg etc. get declared by <unistd.h>.
        * m4/getopt.m4 (gl_GETOPT_CHECK_HEADERS): Require
        AC_USE_SYSTEM_EXTENSIONS.
        * modules/getopt (Depends-on): Add 'extensions'.

--- m4/getopt.m4.orig   2009-08-13 01:07:50.000000000 +0200
+++ m4/getopt.m4        2009-08-13 01:07:32.000000000 +0200
@@ -1,4 +1,4 @@
-# getopt.m4 serial 19
+# getopt.m4 serial 20
 dnl Copyright (C) 2002-2006, 2008-2009 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -41,6 +41,9 @@
 # Determine whether to replace the entire getopt facility.
 AC_DEFUN([gl_GETOPT_CHECK_HEADERS],
 [
+  dnl Persuade Solaris <unistd.h> to declare optarg, optind, opterr, optopt.
+  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
+
   gl_replace_getopt=
   if test -z "$gl_replace_getopt"; then
     AC_CHECK_HEADERS([getopt.h], [], [gl_replace_getopt=yes])
--- modules/getopt.orig 2009-08-13 01:07:50.000000000 +0200
+++ modules/getopt      2009-08-13 01:01:34.000000000 +0200
@@ -11,6 +11,7 @@
 Depends-on:
 gettext-h
 unistd
+extensions
 
 configure.ac:
 gl_GETOPT