mac上安装glfw

1. 安装xcode

2. 安装cmake

3. git clone https://github.com/glfw/glfw.git

4. cd <glfw_dir>; mkdir build; cd build

5. cmake ..

6. cmake -C cmake**install.cmake

7. cd <test_dir>; cp <glfw_dir>/examples/simple.c .

8. cc -o simple simple.c -lglfw3 -framework Cocoa -framework OpenGL -framework IOKit -framework CoreVideo