`flock` LOCK_SH, LOCK_EX, LOCK_UN options are exclusive

[mvorisek]

Feature request

repro: https://phpstan.org/r/9a616a84-4e70-4c5f-aa49-4be418b1745e

I would expect phpstan to emit an error as the LOCK_SH, LOCK_EX, LOCK_UN options are exclusive.

Only the LOCK_NB option can be combined and cannot be used alone.

So the function should accept only 6 constant options.