Suggested patch for FindOpenGL.cmake

[Brad King]

David Faure wrote:
> Why look for X11 again, if we did so already before?
[snip]
>    IF (OPENGL_gl_LIBRARY)
> -    INCLUDE(FindX11)
> +    IF (NOT X11_FOUND)
> +      INCLUDE(FindX11)
> +    ENDIF (NOT X11_FOUND)

This fix will be in CMake 2.4.3.

-Brad