Codechange: be consistent in naming the paint function Paint()

Also move this function to be a class member. This to allow
further deduplicating of code in a later commit.

src/video/sdl2_v.cpp

@@ -124,7 +124,7 @@ void VideoDriver_SDL::CheckPaletteAnim()
 	this->MakeDirty(0, 0, _screen.width, _screen.height);
 }
 
-static void Paint()
+void VideoDriver_SDL::Paint()
 {
 	PerformanceMeasurer framerate(PFE_VIDEO);
 
@@ -161,7 +161,7 @@ static void Paint()
 	MemSetT(&_dirty_rect, 0);
 }
 
-static void PaintThread()
+void VideoDriver_SDL::PaintThread()
 {
 	/* First tell the main thread we're started */
 	std::unique_lock<std::recursive_mutex> lock(*_draw_mutex);
@@ -172,11 +172,16 @@ static void PaintThread()
 
 	while (_draw_continue) {
 		/* Then just draw and wait till we stop */
-		Paint();
+		this->Paint();
 		_draw_signal->wait(lock);
 	}
 }
 
+/* static */ void VideoDriver_SDL::PaintThreadThunk(VideoDriver_SDL *drv)
+{
+	drv->PaintThread();
+}
+
 static const Dimension default_resolutions[] = {
 	{  640,  480 },
 	{  800,  600 },
@@ -820,7 +825,7 @@ void VideoDriver_SDL::LoopOnce()
 		if (_draw_mutex != nullptr && !HasModalProgress()) {
 			_draw_signal->notify_one();
 		} else {
-			Paint();
+			this->Paint();
 		}
 	}
 
@@ -861,7 +866,7 @@ void VideoDriver_SDL::MainLoop()
 			_draw_signal = new std::condition_variable_any();
 			_draw_continue = true;
 
-			_draw_threaded = StartNewThread(&draw_thread, "ottd:draw-sdl", &PaintThread);
+			_draw_threaded = StartNewThread(&draw_thread, "ottd:draw-sdl", &VideoDriver_SDL::PaintThreadThunk, this);
 
 			/* Free the mutex if we won't be able to use it. */
 			if (!_draw_threaded) {