[compiler-rt] [compiler-rt] Define `__STDC_FORMAT_MACROS` to ensure `PRId64` is available (PR #102980)

[Florian Mayer via llvm-commits]

fmayer wrote:

I think your email address is still the GitHub alias @giordano

See https://github.com/llvm/llvm-project/pull/102980#issuecomment-2284928642 

https://github.com/llvm/llvm-project/pull/102980