[libclc] [libclc] Use custom CMake handling to overhaul libclc compilation (PR #185247)

[Matt Arsenault via cfe-commits]

arsenm wrote:

I've already forgotten all about that and it's not even been a month. This is just a rename, those were all the same monolithic libclc.bc. The total number has decreased since the dead targets have been removed 

https://github.com/llvm/llvm-project/pull/185247