Yes, I’d been pretty much performing the same diagnosis in parallel - it seems we just don’t have that libLLVMSupport library built.
Last night, tried the build of clang a few different ways to get that library built - including specifying the --gcc-toolchain option. No Joy!
Which of the clang/llvm source trees provides it? or is it in another source package? tools? Is there a Special Sauce which I must cook up?
(have changed topic title to re-focus on the core issue here!)