[llvm] [WIP][SPARC] Allow overaligned `alloca`s (PR #107223)

[Rainer Orth via llvm-commits]

rorth wrote:

Just for reference, I've posted the patches I've used for my ASan testing: PR #107403 for the driver side and PR #107405 for enabling the ASan tests in `compiler-rt`.

https://github.com/llvm/llvm-project/pull/107223