Build: Update getopt.m4 from Gnulib.

This file was modified from upstream since we do not need to replace
getopt() and can avoid complexity and feature tests.

m4/getopt.m4

@@ -1,71 +1,70 @@
-# getopt.m4 serial 14 (modified version)
-dnl Copyright (C) 2002-2006, 2008 Free Software Foundation, Inc.
+# getopt.m4 serial 49 (modified version)
+dnl Copyright (C) 2002-2006, 2008-2023 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.
 
-# The getopt module assume you want GNU getopt, with getopt_long etc,
-# rather than vanilla POSIX getopt.  This means your code should
-# always include <getopt.h> for the getopt prototypes.
+# This version has been modified to reduce complexity since we only need
+# GNU getopt_long and do not care about replacing getopt.
 
-AC_DEFUN([gl_GETOPT_SUBSTITUTE],
+# Check for a POSIX compliant getopt function with GNU extensions (such as
+# options with optional arguments) and the functions getopt_long,
+# getopt_long_only.
+AC_DEFUN([gl_FUNC_GETOPT_GNU],
 [
-  AC_LIBOBJ([getopt])
-  AC_LIBOBJ([getopt1])
-  gl_GETOPT_SUBSTITUTE_HEADER
-])
+  AC_REQUIRE([gl_GETOPT_CHECK_HEADERS])
 
-AC_DEFUN([gl_GETOPT_SUBSTITUTE_HEADER],
-[
-  GETOPT_H=getopt.h
-  AC_DEFINE([__GETOPT_PREFIX], [[rpl_]],
-    [Define to rpl_ if the getopt replacement functions and variables
-     should be used.])
-  AC_SUBST([GETOPT_H])
+  if test -n "$gl_replace_getopt"; then
+    gl_GETOPT_SUBSTITUTE
+  fi
 ])
 
 AC_DEFUN([gl_GETOPT_CHECK_HEADERS],
 [
-  if test -z "$GETOPT_H"; then
-    AC_CHECK_HEADERS([getopt.h], [], [GETOPT_H=getopt.h])
+  gl_replace_getopt=
+
+  if test -z "$gl_replace_getopt"; then
+    AC_CHECK_HEADERS([getopt.h], [], [gl_replace_getopt=yes])
   fi
 
-  if test -z "$GETOPT_H"; then
-    AC_CHECK_FUNCS([getopt_long], [], [GETOPT_H=getopt.h])
+  if test -z "$gl_replace_getopt"; then
+    AC_CHECK_FUNCS([getopt_long], [], [gl_replace_getopt=yes])
   fi
 
   dnl BSD getopt_long uses a way to reset option processing, that is different
   dnl from GNU and Solaris (which copied the GNU behavior). We support both
   dnl GNU and BSD style resetting of getopt_long(), so there's no need to use
   dnl GNU getopt_long() on BSD due to different resetting style.
-  dnl
-  dnl With getopt_long(), some BSD versions have a bug in handling optional
-  dnl arguments. This bug appears only if the environment variable
-  dnl POSIXLY_CORRECT has been set, so it shouldn't be too bad in most
-  dnl cases; probably most don't have that variable set. But if we actually
-  dnl hit this bug, it is a real problem due to our heavy use of optional
-  dnl arguments.
-  dnl
-  dnl According to CVS logs, the bug was introduced in OpenBSD in 2003-09-22
-  dnl and copied to FreeBSD in 2004-02-24. It was fixed in both in 2006-09-22,
-  dnl so the affected versions shouldn't be popular anymore anyway. NetBSD
-  dnl never had this bug. TODO: What about Darwin and others?
-  if test -z "$GETOPT_H"; then
+  if test -z "$gl_replace_getopt"; then
     AC_CHECK_DECL([optreset],
       [AC_DEFINE([HAVE_OPTRESET], 1,
         [Define to 1 if getopt.h declares extern int optreset.])],
       [], [#include <getopt.h>])
   fi
 
-  dnl Solaris 10 getopt doesn't handle `+' as a leading character in an
-  dnl option string (as of 2005-05-05). We don't use that feature, so this
+  dnl POSIX 2008 does not specify leading '+' behavior, but see
+  dnl http://austingroupbugs.net/view.php?id=191 for a recommendation on
+  dnl the next version of POSIX.  We don't use that feature, so this
   dnl is not a problem for us. Thus, the respective test was removed here.
+
+  dnl Checks for getopt handling `-' as a leading character in an option
+  dnl string were removed, since we also don't use that feature.
+
 ])
 
-AC_DEFUN([gl_GETOPT_IFELSE],
+AC_DEFUN([gl_GETOPT_SUBSTITUTE],
 [
-  AC_REQUIRE([gl_GETOPT_CHECK_HEADERS])
-  AS_IF([test -n "$GETOPT_H"], [$1], [$2])
+  AC_LIBOBJ([getopt])
+  AC_LIBOBJ([getopt1])
+
+  AC_CHECK_HEADERS_ONCE([sys/cdefs.h])
+
+  AC_DEFINE([__GETOPT_PREFIX], [[rpl_]],
+    [Define to rpl_ if the getopt replacement functions and variables
+     should be used.])
+
+  GETOPT_H=getopt.h
+  AC_SUBST([GETOPT_H])
 ])
 
-AC_DEFUN([gl_GETOPT], [gl_GETOPT_IFELSE([gl_GETOPT_SUBSTITUTE])])
+AC_DEFUN([gl_GETOPT], [gl_FUNC_GETOPT_GNU])