osl_transform_triple(), osl_transform_dvmdv() and so on are supposed to apply
the given transform in the context of OSL's auto-differentiation system.
Therefore, the given input is a dual vector, containing both the value as v[0]
and its derivatives w.r.t. X and Y in v[1] and v[2].
However, the existing code treats these as a simple list of vectors, applying
the same operation to all three instead of propagating the derivatives.
On top of that, it also treated the given matrix input as if there were three
of them, which isn't the case.
Therefore, this commit replaces the implementation to do the right thing.
The Vector and Normal case are straightforward since the operation is linear,
so applying the same operation to all three vectors works.
The Point case is a bit more complicated, but not too bad when written out.
This bug mostly became apparent when using Object or Camera texture coordinates
with a Bump node, since that node uses OSL differentials and Object/Camera
coordinates are implemented using transform().
I'm pretty sure that all the other builtin functions (e.g. sin) at the bottom
of services_gpu.h have the same problem, but one thing at a time...
Pull Request: https://projects.blender.org/blender/blender/pulls/138045
8bc9f174d3