[clang] [clang] Limit alignment for emitted vectors (PR #98629)

[Eli Friedman via cfe-commits]

efriedma-quic wrote:

The size of ArgFlagsTy is, as far as I can tell, basically irrelevant: it's only used as part of computing the calling convention in isel.  I don't think anyone will notice if it's a few bytes larger.

The non-byval alignment limit was last adjusted in https://reviews.llvm.org/D110451 .

https://github.com/llvm/llvm-project/pull/98629