libcamera: thread: Enforce dispatchMessages() call context with assert

The Thread::dispatchMessages() function is meant to be called from
within the thread only. Catch incorrect usage with an ASSERT().

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Hirokazu Honda <hiroh@chromium.org>

src/libcamera/thread.cpp

@@ -560,6 +560,8 @@ void Thread::removeMessages(Object *receiver)
  */
 void Thread::dispatchMessages(Message::Type type)
 {
+	ASSERT(data_ == ThreadData::current());
+
 	MutexLocker locker(data_->messages_.mutex_);
 
 	std::list<std::unique_ptr<Message>> &messages = data_->messages_.list_;