Implement tryadd, adding itmes with a timeout

include/ucore/ucore_threadqueue.h

@@ -166,11 +166,19 @@ int uc_thread_queue_init(struct uc_threadqueue *queue, long max_elements);
  * the front of the queue, i.e. it can be considered a "priority" message.
  *
  * @param queue Pointer to the queue on where the message should be added.
+ * @param timeout timeout on how long to wait on a message, or NULL for no timeout
  * @param data the "message".
- * @return 0 on succes ENOMEM if out of memory EINVAL if queue is NULL, or other
+ * @return 0 on succes ENOMEM if out of memory EINVAL if queue is NULL, ETIMEDOUT if timeout occured or other
  * errno values if pthread functions failed.
  */
-int uc_thread_queue_add(struct uc_threadqueue *queue, struct uc_threadmsg *msg);
+int uc_thread_queue_tryadd(struct uc_threadqueue *queue, const struct timespec *timeout, struct uc_threadmsg *msg);
+
+/** 
+ * Like uc_thread_queue_add but will wait indefintly.
+ * @see uc_thread_queue_add
+ */
+#define uc_thread_queue_add(queue, msg)\
+uc_thread_queue_tryadd(queue, NULL, msg)
 
 /**
  * Gets a message from a queue