Fixed bug #252: menu windows are drawn with immediate mode and the fixed

function pipeline, and therefore we must make sure the context created for them
is not a core profile context. Previously if the user requested a core profile
context, this would apply to menu windows too, and they would appear black.

git-svn-id: svn+ssh://svn.code.sf.net/p/freeglut/code/trunk/freeglut/freeglut@1855 7f0cb862-5218-0410-a997-914c9d46530a