[llvm] [LLVM][SVE] Honour calling convention when using SVE for fixed length vectors. (PR #70847)

[Paul Walker via llvm-commits]

paulwalker-arm wrote:

To aid review I've split the tests into a separate patch, albeit they don't show the existing broken output because many of the tests trigger internal compiler errors and the existing output does not really matter because it's wrong.

https://github.com/llvm/llvm-project/pull/70847