Preprocessing for libpng
预处理libpng

Signed-off-by: Wanpeng Song <swpustc@mail.ustc.edu.cn>
add a file ext list for non removed
添加一个不删除的后缀名列表

Signed-off-by: Wanpeng Song <swpustc@mail.ustc.edu.cn>
Add remove unneeded files script
添加移除不需要的文件脚本

Signed-off-by: Wanpeng Song <swpustc@mail.ustc.edu.cn>
Fix processing script
修正预处理脚本

Signed-off-by: Wanpeng Song <swpustc@mail.ustc.edu.cn>