semctl(..., SETVAL, …) with current PID as value is error prone

[dmedvinsky]

There is SEMVMX, which is semaphore value max, which can be less than the PID we get. We should get rid of this hack and use the built-in semctl(..., GETPID, ...).

We would need to do some fake semop, though, for it to work, but I see some logic in this, so it's OK.