should be sizeof(sigset_t)
I was reading the glibc source and verifying strace output, `1*sizeof(unsigned long)` is correct in this case for NULL sigset.
But yes, hardcoding the syscall number is a bad idea, and the issue with the linux-32 tests is that epoll_pwait2 only takes 64-bit timespecs (which the glibc wrapper automatically converts). I'll undraft it when I revise the approach.