错误提示：
Cannot find autoconf. Please check your autoconf installation and the
$PHP_AUTOCONF environment variable. Then, rerun this script.
解决方法：
curl -OL http://ftpmirror.gnu.org/autoconf/autoconf-latest.tar.gztar xzf autoconf-latest.tar.gz
cd autoconf-*./configure –prefix=/usr/local
make
sudo make install […]