Document the return type coding style.

As per discussion at [0] methods shouldn't use OpenGL return types, if
they're not part of the GL API.

[0] <http://marc.info/?l=mesa3d-dev&m=130754488901774&w=2>

Signed-off-by: Kai Wasserbäch <kai@dev.carbon-project.org>
Signed-off-by: Ian Romanick <ian.d.romanick@intel.com>
1 file changed