[libclc] [libclc] Remove bitcode prepare utility from OpenCL library build (PR #174447)

[Matt Arsenault via cfe-commits]

arsenm wrote:

rocm-device-libs also has some weird wchar_size hack (such that we also do not have the same bitcode depending on if the build host is windows or not), I've never understood why that's a thing. Especially given wchar_size isn't even an OpenCL type 

https://github.com/llvm/llvm-project/pull/174447