[llvm] [NFC] Suppress spurious deprecation warning with MSVC (PR #124764)

[Stephen Tozer via llvm-commits]

SLTozer wrote:

Is there a way to suppress this warning/error without changing getFirstNonPHI to be defined out-of-line? Also, it seems odd to me that doing so results in the MSVC diagnostic being suppressed, do you have a reference to the buildbot (if any) where these problems appeared?

https://github.com/llvm/llvm-project/pull/124764