安装PECL Memcached错误

我按照以下步骤在我的Centos Server中安装PECL memcached,总是出错.

第一.安装libmemcached

cd /opt
wget http://launchpad.net/libmemcached/1.0/0.40a/+download/libmemcached-0.40.tar.gz
tar -xzvf libmemcached-0.40.tar.gz
cd libmemcached-0.40
./configure
make
make install

其次,安装PECL memcached

cd /opt
pecl download memcached-1.0.2
tar zxvf memcached-1.0.2.tgz
cd memcached-1.0.2
phpize
./configure --with-libmemcached-dir=/opt/libmemcached-0.40/libmemcached

我总是有错误

checking for memcached igbinary support... disabled
configure: error: Can't find libmemcached headers under "/opt/libmemcached-0.40/libmemcached"

实际上memcached.h档案是/opt/libmemcached-0.40/libmemcached擅自的.

请指教.