Fix updates of dynamic media player

Author: ryancheung

src/FNAPlatform/SDL2_FNAPlatform.cs

@@ -382,6 +382,7 @@ public static void ProgramExit(object sender, EventArgs e)
 				SoundEffect.FAudioContext.Context.Dispose();
 			}
 			Media.MediaPlayer.DisposeIfNecessary();
+			Media.DynamicMediaPlayer.DisposeIfNecessary();
 
 			// This _should_ be the last SDL call we make...
 			SDL.SDL_Quit();

src/FrameworkDispatcher.cs

@@ -55,14 +55,17 @@ public static void Update()
 			}
 
 			Media.MediaPlayer.Update();
+			Media.DynamicMediaPlayer.Update();
 			if (ActiveSongChanged)
 			{
 				Media.MediaPlayer.OnActiveSongChanged();
+				Media.DynamicMediaPlayer.OnActiveSongChanged();
 				ActiveSongChanged = false;
 			}
 			if (MediaStateChanged)
 			{
 				Media.MediaPlayer.OnMediaStateChanged();
+				Media.DynamicMediaPlayer.OnMediaStateChanged();
 				MediaStateChanged = false;
 			}