Based on my (admittedly extremely limited) understanding of things, this seems correct as is:

#if defined(__x86_64__) || defined(__aarch64__)
    case __NR_newfstatat:  // fstatat(). EPERM not a valid errno.
#elif defined(__i386__) || defined(__arm__) || \
    (defined(ARCH_CPU_MIPS_FAMILY) && defined(ARCH_CPU_32_BITS))
    case __NR_fstatat64:
#endif

Is fstatat64 actually implemented on x86_64 now?

Alternately, if you'd prefer to simply open an upstream bug with Google, just let me know. :) I want to be helpful here, but not waste your time.

Thanks,
~spot