common: pthread_cond_signal: don't need lock

common: pthread_cond_signal: don't need lock

from the man page:

The pthread_cond_broadcast() or pthread_cond_signal() functions may be
called by a thread whether or not it currently owns the mutex that
threads calling pthread_cond_wait() or pthread_cond_timedwait() have
associated with the condition variable during their waits.

The man page goes on to suggest that sometimes you might want to hold
the lock when signalling. This would be the case if you had some
other variable that could only change when the lock was held, and you
wanted to ensure that that variable did not change prior to the waiter
being woken. That is not the case here, so it's irrelevant.

Signed-off-by: Colin McCabe <colin.mccabe@dreamhost.com>