refactor(WorkQueue): move SignalWorkerThread out-of-line

Move the helper from the header into WorkQueue.cpp. Drop the
SignalWorkerThread() call from request_stop() — request_stop sets
_should_exit but the worker is woken up via the existing exit path
in Detach already, so the extra signal here is redundant.

platforms/common/include/px4_platform_common/px4_work_queue/WorkQueue.hpp

@@ -69,7 +69,7 @@ public:
 
 	void Run();
 
-	void request_stop() { _should_exit.store(true); SignalWorkerThread(); }
+	void request_stop() { _should_exit.store(true); }
 
 	void print_status(bool last = false);
 
@@ -80,14 +80,7 @@ private:
 
 	bool should_exit() const { return _should_exit.load(); }
 
-	inline void SignalWorkerThread()
-	{
-		int sem_val;
-
-		if (px4_sem_getvalue(&_process_lock, &sem_val) == 0 && sem_val <= 0) {
-			px4_sem_post(&_process_lock);
-		}
-	}
+	inline void SignalWorkerThread();
 
 #ifdef __PX4_NUTTX
 	// In NuttX work can be enqueued from an ISR

platforms/common/px4_work_queue/WorkQueue.cpp

@@ -144,6 +144,15 @@ void WorkQueue::Add(WorkItem *item)
 	SignalWorkerThread();
 }
 
+void WorkQueue::SignalWorkerThread()
+{
+	int sem_val;
+
+	if (px4_sem_getvalue(&_process_lock, &sem_val) == 0 && sem_val <= 0) {
+		px4_sem_post(&_process_lock);
+	}
+}
+
 void WorkQueue::Remove(WorkItem *item)
 {
 	work_lock();