[clang] [X86][vectorcall] Do not consume register for indirect return value (PR #97939)

[Eli Friedman via cfe-commits]

https://github.com/efriedma-quic approved this pull request.

LGTM

I meant, at the beginning of X86_32ABIInfo::computeInfo there's a chain of if statements that set up the properties of different calling conventions, and maybe some bits could be set there.  If you don't think that makes sense, though, it's fine.

https://github.com/llvm/llvm-project/pull/97939