libcamera: base: thread: Support dispatching for a specific receiver

The Thread::dispatchMessage() function supports filtering messages based
on their type. It can be useful to also dispatch only messages posted
for a specific receiver. Add an optional receiver argument to the
dispatchMessage() function to do so. When set to null (the default
value), the behaviour of the function is not changed.

This facility is actually used in followup patches.

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

include/libcamera/base/thread.h

@@ -48,7 +48,8 @@ public:
 
 	EventDispatcher *eventDispatcher();
 
-	void dispatchMessages(Message::Type type = Message::Type::None);
+	void dispatchMessages(Message::Type type = Message::Type::None,
+			      Object *receiver = nullptr);
 
 protected:
 	int exec();