[tsan] Refine fstat{,64} interceptors (#86625)

[tsan] Refine fstat{,64} interceptors (#86625)

In glibc versions before 2.33. `libc_nonshared.a` defines
`__fxstat/__fxstat64` but there is no `fstat/fstat64`. glibc 2.33 added
`fstat/fstat64` and obsoleted `__fxstat/__fxstat64`. Ports added after
2.33 do not provide `__fxstat/__fxstat64`, so our `fstat/fstat64`
interceptors using `__fxstat/__fxstat64` interceptors would lead to
runtime failures on such ports (LoongArch and certain RISC-V ports).

Similar to https://reviews.llvm.org/D118423, refine the conditions that
we define fstat{,64} interceptors. `fstat` is supported by musl/*BSD
while `fstat64` is glibc only.

(cherry picked from commit d5224b73ccd09a6759759791f58426b6acd4a2e2)