[compiler-rt] [tsan] Refine fstat{, 64} interceptors on GLIBC (PR #85612)

[via llvm-commits]

wangleiat wrote:

> > Without this patch, use-of-uninitialized value will occur on those architectures, which are supported by Glibc since version 2.33. Because they have no opportunity to implement the __fxstat{,64} interfaces.
> 
> "those architectures" are not clear. I assume they include LoongArch (base version 2.36) and some RISC-V variants (`sysdeps/unix/sysv/linux/riscv/shlib-versions`)
> 
> This description needs rewording. I think there may be a difference if a glibc port has a base version >= 2.33. https://maskray.me/blog/2022-05-29-glibc#buildabi-versions.h
> 
> Can you describe what `f*stat` symbols your glibc port defines?

Thank you very much for your blog; I've learned a lot from it. I've attempted to modify the commit message using my limited English vocabulary.

https://github.com/llvm/llvm-project/pull/85612