This port will be removed on 2020-12-31 if not fixed
It's optional build dependency.
A commit references this bug:
Date: Fri Jan 1 14:15:10 UTC 2021
New revision: 559828
emulators/virtualbox-ose-additions: drop optional support for OPENGL
OPENGL requires Python 2.7 which expired yesterday.
Submitted by: swills (hint by VVD)
Option for OpenGL dropped from this port, thanks for the hint.