pthread: Fix deadlock during thread initialization

Sometimes, if pthread_create() failed, then pthread_cond_wait() could
accidentally be called in the worker threads after the uninit function
had already called pthread_cond_broadcast(), leading to a deadlock.

Don't call pthread_cond_wait() if c->done is set.
Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>

libavcodec/pthread.c

@@ -152,6 +152,7 @@ static void* attribute_align_arg worker(void *v)
             if (c->current_job == thread_count + c->job_count)
                 pthread_cond_signal(&c->last_job_cond);
 
+            if (!c->done)
                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
             our_job = self_id;
 

libavfilter/pthread.c

@@ -73,6 +73,7 @@ static void* attribute_align_arg worker(void *v)
             if (c->current_job == nb_threads + c->nb_jobs)
                 pthread_cond_signal(&c->last_job_cond);
 
+            if (!c->done)
                 pthread_cond_wait(&c->current_job_cond, &c->current_job_lock);
             our_job = self_id;