The macro is not defined on older OSX versions and evaluates to 0.
https://bugzilla.gnome.org/show_bug.cgi?id=740201
# if __APPLE__
# include <OpenGL/OpenGL.h>
# include <OpenGL/gl.h>
-# if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_7
+# if MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
# define GL_DO_NOT_WARN_IF_MULTI_GL_VERSION_HEADERS_INCLUDED
# include <OpenGL/gl3.h>
# endif
# ifdef __APPLE__
# include <OpenGL/OpenGL.h>
# include <OpenGL/gl.h>
-# if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_7
+# if MAC_OS_X_VERSION_MAX_ALLOWED >= 1070
# define GL_DO_NOT_WARN_IF_MULTI_GL_VERSION_HEADERS_INCLUDED
# include <OpenGL/gl3.h>
# endif