一、下载libcurl http://curl.haxx.se/download/curl-7.21.1.tar.gz
二、安装 指定了安装目录 /usr/local/curl
命令1: ./configure --prefix=/usr/local/curl
命令2：make
命令3：sudo make install
可以看到lib库，已经安装在 /usr/local/curl/lib
Libraries have been installed in:
/usr/local/curl/lib
在安装目录下/usr/local/curl下会有四个目录 bin include lib share 包含了所需的库、头文件等