When blender is compiled with `WITH_OPENSUBDIV=Off` Blender just works
fine. However when compiling all the static shaders the OpenSubDiv
shaders are also compiled and fail as they rely on OpenSubDiv.
This PR fixes this by only adding the shaders when OpenSubDiv is
available.
This issue could be reproduced using the `--debug-gpu-compile-shaders`
option or running GPU test cases.
Pull Request: https://projects.blender.org/blender/blender/pulls/135285
e866137cc8