Note:

The 2.9.x series is the development release and using 2.9.10 in particular
broke the simgear build. OpenSceneGraph 2.8.4 is the latest stable release
and simgear can be build with it.

Note:

OpenSceneGraph is using cmake for building but they provide one-liner
configure script which is calling 'cmake -DCMAKE_BUILD_TYPE=Release'.
We do not want to run this configure script because our automatically
generated cmake options will be ommited, thus we are relying on our
integrated automatic cmake handling.