OpenEXR has some dependecies that other other modules in Blender
requires. When disabling OpenEXR these dependecies could not match
and building blender would fail.
This PR disables the next options when WITH_IMAGE_OPENEXR=Off
- `WITH_OPENVDB`
- `WITH_ALEMBIC`
- `WITH_VULKAN_BACKEND`
- `WITH_CYCLES_OSL`
Additionally windows stores the IMath libraries in `IMATH_LIBRARIES`
Linux and Mac stored the IMath libraries in `IMATH_LIBRARY`. This
change will also adds `IMATH_LIBRARIES` variable to all platforms.