[clang] fix bug that undefined internal is a warning only for -pedantic-errors (PR #98016)

[via cfe-commits]

dyung wrote:

> Yup, that resolved the issue: https://lab.llvm.org/buildbot/#/builders/144/builds/2082 -- not certain why that builder has a different default value for `-std` though. Clang defaults to C17, but that builder seems to be defaulting to C99.

This bot targets the PS4 which has kept an older version of the standard as the default for compatibility reasons. 


https://github.com/llvm/llvm-project/pull/98016