CentOS6.9升级autoconf版本，解决”Autoconf version 2.64 or higher is required“错误

安装软件时提示说需要Autoconf 2.64或更高的版本：

 # autoconf
 configure.ac:: error: Autoconf version 2.64 or higher is required
 configure.ac:: the top level
 autom4te: /usr/bin/m4 failed with exit status:  

查询当前版本：

 # rpm -qf /usr/bin/autoconf
 autoconf-2.63-5.1.el6.noarch  

卸载当前版本：

 # rpm -e --nodeps autoconf-2.63

安装最新版本：

 # wget https://ftp.gnu.org/gnu/autoconf/autoconf-2.69.tar.gz
 # tar zxvf autoconf-2.69.tar.gz
 # cd autoconf-2.69
 # ./configure
 # make && make install  

查看当前版本：

 # /usr/bin/autoconf -V
     autoconf (GNU Autoconf) 2.69
     Copyright (C)  Free Software Foundation, Inc.
     License GPLv3+/Autoconf: GNU GPL version  or later
     <http://gnu.org/licenses/gpl.html>, <http://gnu.org/licenses/exceptions.html>
     This is free software: you are free to change and redistribute it.
     There is NO WARRANTY, to the extent permitted by law.  

     Written by David J. MacKenzie and Akim Demaille.  

至此，autoconf已升级到2.69