configure 时出现以下错误：
checking for autoconf... no
configure: error:
*** These critical programs are missing or too old: as ld
*** Check the INSTALL file for required versions.问题原因：
缺少autoconf或版本太低
下载安装新版本
# wget ftp://ftp.gnu.org/gnu/autoconf/autoconf-2.68.tar.gz
# tar zxvf autoconf-2.68.tar.gz
# cd autoconf-2.68
# ./configure --prefix=/usr/
# make && make install查看当前版本：
# autoconf -V
autoconf (GNU Autoconf) 2.68
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+/Autoconf: GNU GPL version 3 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.注意是大写的V。