[libclc] [libclc] Set OpenCL C version for each target (PR #135733)

[Fraser Cormack via cfe-commits]

https://github.com/frasercrmck commented:

Yes I think on reflection it's probably okay to compile for the highest supported OpenCL C version. I believe they're supersets of one another, so a 3.0 builtins library would still contain all of the 1.2 builtins? I might be missing some of the nitty gritty here though.

Another question would be whether or not we should be advertising a 2.X or 3.X library if we don't have all the builtins? Is this a degradation? That might depend on downstream toolchains and if/how they react to versioning info in the LLVM IR.

https://github.com/llvm/llvm-project/pull/135733