gold: configury: fix obsolete macros

Running `autoreconf -vf -Wall' in the gold directory shows errors about the use
of obsolete macros.  This patch fix the issues with macros used directly by
configure.ac. However, it doesn't fix all warnings.  There are autoconf warnings
about macros from files in config and one automake warning about a target being
shadowed.  It cuts a lot of the noise down and makes an upgrade to autoconf
2.71+ easier.

https://www.gnu.org/software/automake/manual/1.12.2/html_node/Obsolete-Macros.html#index-AM_005fCONFIG_005fHEADER
https://www.gnu.org/software/autoconf/manual/autoconf-2.69/html_node/Obsolete-Macros.html#index-AC_005fOUTPUT-2133

gold/ChangeLog:

* aclocal.m4: Regenerate.
	* configure: Regenerate.
	* configure.ac: Replace AM_CONFIG_HEADER by AC_CONFIG_HEADERS. Replace
        AC_OUTPUT(file list) by AC_CONFIG_FILES([file list])\nAC_OUTPUT.

Approved-by: Alan Modra <amodra@gmail.com>

gold/aclocal.m4

@@ -751,35 +751,6 @@ else
 fi
 ])
 
-#  -*- Autoconf -*-
-# Obsolete and "removed" macros, that must however still report explicit
-# error messages when used, to smooth transition.
-#
-# Copyright (C) 1996-2017 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.
-
-AC_DEFUN([AM_CONFIG_HEADER],
-[AC_DIAGNOSE([obsolete],
-['$0': this macro is obsolete.
-You should use the 'AC][_CONFIG_HEADERS' macro instead.])dnl
-AC_CONFIG_HEADERS($@)])
-
-AC_DEFUN([AM_PROG_CC_STDC],
-[AC_PROG_CC
-am_cv_prog_cc_stdc=$ac_cv_prog_cc_stdc
-AC_DIAGNOSE([obsolete],
-['$0': this macro is obsolete.
-You should simply use the 'AC][_PROG_CC' macro instead.
-Also, your code should no longer depend upon 'am_cv_prog_cc_stdc',
-but upon 'ac_cv_prog_cc_stdc'.])])
-
-AC_DEFUN([AM_C_PROTOTYPES],
-         [AC_FATAL([automatic de-ANSI-fication support has been removed])])
-AU_DEFUN([fp_C_PROTOTYPES], [AM_C_PROTOTYPES])
-
 # Helper functions for option handling.                     -*- Autoconf -*-
 
 # Copyright (C) 2001-2017 Free Software Foundation, Inc.

gold/configure

@@ -13590,6 +13590,7 @@ DEFS=-DHAVE_CONFIG_H
 
 ac_libobjs=
 ac_ltlibobjs=
+U=
 for ac_i in : $LIBOBJS; do test "x$ac_i" = x: && continue
   # 1. Remove the extension, and $U if already installed.
   ac_script='s/\$U\././;s/\.o$//;s/\.obj$//'

gold/configure.ac

@@ -25,7 +25,7 @@ AC_CANONICAL_TARGET
 AM_INIT_AUTOMAKE([no-dist parallel-tests])
 AM_SILENT_RULES([yes])
 
-AM_CONFIG_HEADER(config.h:config.in)
+AC_CONFIG_HEADERS([config.h:config.in])
 
 AC_USE_SYSTEM_EXTENSIONS
 
@@ -737,4 +737,5 @@ AM_LC_MESSAGES
 
 AM_MAINTAINER_MODE
 
-AC_OUTPUT(Makefile testsuite/Makefile po/Makefile.in:po/Make-in)
+AC_CONFIG_FILES([Makefile testsuite/Makefile po/Makefile.in:po/Make-in])
+AC_OUTPUT