[clang] [SPARC] use `divideCeil` to calculate register offset (PR #213739)

[Folkert de Vries via cfe-commits]

folkertdev wrote:

Actually, I don't think this can be handled correctly without much larger changes. The alignment of a `typedef` is not available to the ABI code. 

That's not something I'm comfortable with taking on (and also not relevant for Rust FFI), so could fixing that be deferred?

https://github.com/llvm/llvm-project/pull/213739