Similar to 5e46e3d28a.
This commit replaces the C-API version of `OpenSubdiv_Evaluator`
with direct calls to `EvalOutputAPI`. This removes a level of indirection,
theoretically reducing function call overhead, but also making the whole
system easier to understand and easier to modify. The downside is
further spread of `WITH_OPENSUBDIV` into the code, but I think that
can be improved in the future relatively easily once more of this sort
of change is finished.
Pull Request: https://projects.blender.org/blender/blender/pulls/128278
509090e7c3