Correctly initialize the mutex using the init function not the unlock one.

This commit was SVN r3493.

src/threads/mutex.c

@@ -33,7 +33,7 @@ static void ompi_mutex_construct(ompi_mutex_t *m)
     pthread_mutex_init(&m->m_lock_pthread, 0);
 #endif
 #if OMPI_HAVE_ATOMIC
-    ompi_atomic_unlock(&m->m_lock_atomic);
+    ompi_atomic_init( &m->m_lock_atomic, OMPI_ATOMIC_UNLOCKED );
 #endif
 }