Remove manual Close method from OggStream

The OggStream interface no longer needs the Close() method.
OpenOggNonstream returns a smart pointer (OggStreamPtr),
so resource cleanup is automatically handled by the destructor.

OggStreamImpl now calls ov_clear in its destructor, making
manual cleanup unnecessary. This commit removes the Close()
method from the interface and its implementation.

source/soundmanager/data/OggData.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2015 Wildfire Games.
+/* Copyright (C) 2025 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -33,10 +33,6 @@ COggData::COggData()
 
 COggData::~COggData()
 {
-	AL_CHECK;
-	if (ogg)
-		ogg->Close();
-
 	AL_CHECK;
 	if ( m_BuffersUsed > 0 )
 		alDeleteBuffers(m_BuffersUsed, &m_Buffer[0]);

source/soundmanager/data/ogg.cpp

@@ -156,11 +156,9 @@ public:
 		Open();
 	}
 
-	Status Close()
+	~OggStreamImpl()
 	{
 		ov_clear(&m_VorbisFile);
-
-		return 0;
 	}
 
 	virtual ALenum Format()

source/soundmanager/data/ogg.h

@@ -34,7 +34,6 @@ public:
 	virtual ALsizei SamplingRate() = 0;
 	virtual bool atFileEOF() = 0;
 	virtual Status ResetFile() = 0;
-  virtual Status Close() = 0;
 
 	/**
 	 * @return bytes read (<= size) or a (negative) Status