Yes, it's quite normal and expected to have something like:
#define GL_GLEXT_PROTOTYPES
#include <GL/GL.h>
If you're trying to write OpenGL 3 compliant code, you'd normally change that to:
#define GL_GLEXT_PROTOTYPES 1
#define GL3_PROTOTYPES 1
#include <GL3/GL3.h>
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…