Comment 7 for bug 1159000

Regarding opengl, turns out that is actually required as well. Though seems like it is more the result of a bug rather than policy.

In order for CMake to fail detecting opengl, I simply moved my libGL.so file. (Which might not be the cleanest way, but hey, it worked.) When running CMake it first told me that it couldn't detect opengl so it would disable it, but later it failed because widelands_all links to opengl. I therefore think we can tweak the error message when opengl is not found to have it no longer say opengl support is disabled and possibly remove the faulty disabling-related instructions.