cmake _GLFW_HAS_GLXGETPROCADDRESS examples

slicol/Games101-Homework-Win Assignment8/CGL/deps/glfw/CMakeLists.txt :396 

check_function_exists(glXGetProcAddress _GLFW_HAS_GLXGETPROCADDRESS)

openglsuperbible/sb7code extern/glfw-3.0.4/CMakeLists.txt :277 

check_function_exists(glXGetProcAddress _GLFW_HAS_GLXGETPROCADDRESS)