It's because you are building with gcc 3.3, while most of the system is built with gcc 4.x. The warning indicates that libGLU is built with a newer gcc than you are using.
You can generally ignore the warning. Although if strange things start to happen, it might be the first place you would look at.
You can generally ignore the warning. Although if strange things start to happen, it might be the first place you would look at.