ulog mavlink: use the px4_sem calls (needed for OSX)

src/modules/mavlink/mavlink_ulog.cpp

@@ -45,7 +45,7 @@
 
 bool MavlinkULog::_init = false;
 MavlinkULog *MavlinkULog::_instance = nullptr;
-sem_t MavlinkULog::_lock;
+px4_sem_t MavlinkULog::_lock;
 const float MavlinkULog::_rate_calculation_delta_t = 0.1f;
 
 
@@ -185,7 +185,7 @@ void MavlinkULog::initialize()
 	if (_init) {
 		return;
 	}
-	sem_init(&_lock, 1, 1);
+	px4_sem_init(&_lock, 1, 1);
 	_init = true;
 }
 

src/modules/mavlink/mavlink_ulog.h

@@ -105,17 +105,17 @@ private:
 
 	static void lock()
 	{
-		do {} while (sem_wait(&_lock) != 0);
+		do {} while (px4_sem_wait(&_lock) != 0);
 	}
 
 	static void unlock()
 	{
-		sem_post(&_lock);
+		px4_sem_post(&_lock);
 	}
 
 	void publish_ack(uint16_t sequence);
 
-	static sem_t _lock;
+	static px4_sem_t _lock;
 	static bool _init;
 	static MavlinkULog *_instance;
 	static const float _rate_calculation_delta_t; ///< rate update interval