兼容macos新版系统，建议修改Makefile文件

[odinxu]

建议修改Makefile文件 PREFIX = /usr 修改为 PREFIX = /usr/local

以兼容macos新版系统，就算是用sudo也禁止写文件到 /usr/bin/ , /usr/share/ , /usr/lib/ 这些目录。

[groverlynn]

/usr is for linux, not for unix/macOS or win plz refer to the cmake file for real paths