Support for building blender with clang on windows on x64 was added
years ago but given there are no active users support has crumbled a
bit.
This PR brings the build system back into working order but upstream
patches in openVDB are still required for a successful build see PR
#120317 for details.
Blender when build with clang the classroom scenes rendered on the cpu
with cycles is seeing a 5% reduction in render time on both an
AMD 7700x and an Intel 14900k.