This OpenGL call synchronize the worker thread of the nvidia blob.
It can be verified on linux with the __GL_THREADED_OPTIMIZATIONS=1 environment variable.
Those errors should not happen on tested drivers.
It was used as a workaround for https://bugs.freedesktop.org/show_bug.cgi?id=94148
If an OpenGL object is created, bound to a binding using the state
tracker, and then destroyed, a newly created object can be assigned the
same numeric handle by OpenGL. However, even though it is a new object,
and thus needs to be bound to the binding again, the state tracker
compared the current and previous handles and concluded that no change
needed to be made, leading to failure to bind objects in certain cases.
This manifested as broken text in VVVVVV, which this commit fixes along
with similar texturing problems in other games.
In OpenGL 3, texturing is always enabled, and this call is invalid.
While it produced no effect in the rest of the execution, it wouldn't
have the intended effect of disabling texturing for that unit. Instead
bind a null texture to the unit.