Fix bug in internal func _tryLock in OpenBSDImpl.swift

[valeriyvan]

pthread_mutex_trylock return 0 on success.

NAME
     pthread_mutex_trylock – attempt to lock a mutex without blocking

SYNOPSIS
     #include <pthread.h>

     int
     pthread_mutex_trylock(pthread_mutex_t *mutex);

DESCRIPTION
     The pthread_mutex_trylock() function locks mutex.  If the mutex is already locked,
     pthread_mutex_trylock() will not block waiting for the mutex, but will return an error
     condition.

RETURN VALUES
     If successful, pthread_mutex_trylock() will return zero, otherwise an error number will
     be returned to indicate the error.

ERRORS
     The pthread_mutex_trylock() function will fail if:

     [EINVAL]           The value specified by mutex is invalid.

     [EBUSY]            Mutex is already locked.

[Azoy]

@swift-ci please smoke test

[finagolfin]

@swift-ci test windows

[valeriyvan]

Should I do something to make this merge?

[finagolfin]

@swift-ci test windows

[finagolfin]

It has to pass CI first, trying again.

[finagolfin]

Thanks @valeriyvan 👍