[libclc] [libclc] Pass -fapprox-func when compiling 'native' builtins (PR #133119)

[Fraser Cormack via cfe-commits]

frasercrmck wrote:

> set_source_files_properties

That's true but since we're compiling with custom commands (I think) the properties won't automatically get picked up.

That said, we could perhaps set the properties as you suggest and retrieve them with `get_source_file_property`. We'd still need to set the properties "explicitly" as the `SOURCES` system isn't well set up to add arbitrary (lists of) stuff on top of the file name. But at least we could do it in the top-level CMakeLists which feels less hacky to me.

I'll play around with it.

https://github.com/llvm/llvm-project/pull/133119