[clang] [AArch64] Match GCC behaviour for zero-size structs (PR #124760)

[Oliver Stannard via cfe-commits]

ostannard wrote:

I agree with @efriedma-quic that this is a very artificial test case, and I wouldn't expect anyone to hit this in reality (I only noticed it while copying the test for #124762), so it's not worth release-noting or adding a compatibility option.

https://github.com/llvm/llvm-project/pull/124760