[clang] [clang] Don't warn on zero literals with -std=c2y (PR #149688)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

> Do you need someone to land this on your behalf?

I'm going to assume yes, but mostly I want to get this pushed so we can backport it to the release branch.

https://github.com/llvm/llvm-project/pull/149688