base: thread: Document the postMessage() function as thread-safe

The Thread::postMessage() function is thread-safe, document it as such.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

src/libcamera/base/thread.cpp

@@ -526,6 +526,8 @@ EventDispatcher *Thread::eventDispatcher()
  *
  * If the \a receiver is not bound to this thread the behaviour is undefined.
  *
+ * \context This function is \threadsafe.
+ *
  * \sa exec()
  */
 void Thread::postMessage(std::unique_ptr<Message> msg, Object *receiver)