This commit adds Epoxy as an explicit library requirement for
`intern/opensubdiv`, which uses it in `gl_compute_evaluator.cc`.
This fixes build errors where lite builds that additionally enabled
OpenSubdiv would fail to link due to missing Epoxy symbols. This
problem did not occur in regular release builds due to other CMake
modules adding Epoxy to the library link path in place of OpenSubdiv.
Pull Request: https://projects.blender.org/blender/blender/pulls/129740
6ccc786e82