继续安装php开发环境，当安装到libpng的时候，输入make命令，确发现提示错误，没有找到makefile。
我还纳闷儿了，明明有makefile.am 和 makefile.in啊，configure以后不就生成makefile了嘛，于是又执行了一遍configure，结果在最后一行发现错误，如下。
configure: error: zlib not installed
google以后，发现大家都是用的这个方法解决：
————————————-华丽丽的分割线，下面是英语版———————–
English Version:
Continue to install the PHP environment.
When install the libpng package after entering the make command, the error “cannot find the makefile” might occur.
I’m so confused~~, the makefile.am and makefile.in obviously exsit in the directory. The makefile should be generated after configuring.
So I perform the configure command again, and then find this error:
configure: error: zlib not installed
Google it, find following solution that many people are using:
1. Enter the directory where the zlib source file is, and perform the make clean command to clean up zlib.
2. Reconfigure using ./configure without –prefix parameter.
3. Perform make and make isntall
4. Enter the libpng directory, execute the command ./configure –prefix=/usr/local/libpng.
5. Perform command make and make install.