Calling FUTEX_LOCK_PI with qemu-x86_64-static caused ENOSYS error.
Description of problem:
When I executed the command "perf bench futex lock-pi" in amd64 docker image on s390x, I got the following error.
```
perf: thread 2: Could not lock pi-lock for 0x40006c4480 (-1): Function not implemented
perf: thread 2: Could not lock pi-lock for 0x40006c4480 (-1): Function not implemented
perf: thread 2: Could not lock pi-lock for 0x40006c4480 (-1): Function not implemented
perf: thread 2: Could not lock pi-lock for 0x40006c4480 (-1): Function not implemented
```

I searched for this error message in the source code of perf-bench. I think that the following system call caused ENOSYS error.
`  syscall(SYS_futex, uaddr, FUTEX_LOCK_PI | opflags, val, timeout, uaddr2, val3)`
Steps to reproduce:
1. Execute the command "perf bench futex lock-pi" in amd64 docker image on s390x
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Additional information: