Honored Contributor Honored Contributor
Re: OpenGL with glut
That symbol is defined in libXext.sl.
In general you should link libraries that need symbols before libraries that define those symbols. It is not always necessary when using shared libraries, because a shared library is brought in as one unit. It is still a good habit. I would list -lXext and -lXi before -lX11. Use this library list in your link line-

-lglut -lGL -lGLU -lXext -lXi -lX11 -lm