- moved sound engine cleanup calls to own function

https://forum.zdoom.org/viewtopic.php?t=66605#p1127457

src/sound/s_advsound.cpp

@@ -742,12 +742,7 @@ void FPlayerSoundHashTable::MarkUsed()
 void S_ClearSoundData()
 {
 	if (soundEngine)
-	{
-		soundEngine->StopAllChannels();
-		soundEngine->UnloadAllSounds();
-		soundEngine->GetSounds().Clear();
-		soundEngine->ClearRandoms();
-	}
+		soundEngine->Clear();
 
 	Ambients.Clear();
 	while (MusicVolumes != NULL)

src/sound/s_sound.cpp

@@ -68,6 +68,20 @@ void SoundEngine::Init(TArray<uint8_t> &curve)
 	S_SoundCurve = std::move(curve);
 }
 
+//==========================================================================
+//
+// SoundEngine::Clear
+//
+//==========================================================================
+
+void SoundEngine::Clear()
+{
+	StopAllChannels();
+	UnloadAllSounds();
+	GetSounds().Clear();
+	ClearRandoms();
+}
+
 //==========================================================================
 //
 // S_Shutdown

src/sound/s_soundinternal.h

@@ -277,6 +277,7 @@ public:
 	//
 	void Init(TArray<uint8_t> &sndcurve);
 	void InitData();
+	void Clear();
 	void Shutdown();
 
 	void StopAllChannels(void);