MusicPipe: automatically clear in destructor

We can implement this now that we have a MusicBuffer reference.

src/MusicPipe.hxx

@@ -67,12 +67,8 @@ public:
 
 	MusicPipe(const MusicPipe &) = delete;
 
-	/**
-	 * Frees the object.  It must be empty now.
-	 */
-	~MusicPipe() {
-		assert(head == nullptr);
-		assert(tail_r == &head);
+	~MusicPipe() noexcept {
+		Clear();
 	}
 
 	MusicPipe &operator=(const MusicPipe &) = delete;

src/output/MultipleOutputs.cxx

@@ -407,11 +407,8 @@ MultipleOutputs::Close() noexcept
 	for (auto *ao : outputs)
 		ao->LockCloseWait();
 
-	if (pipe != nullptr) {
-		pipe->Clear();
-		delete pipe;
-		pipe = nullptr;
-	}
+	delete pipe;
+	pipe = nullptr;
 
 	input_audio_format.Clear();
 
@@ -424,11 +421,8 @@ MultipleOutputs::Release() noexcept
 	for (auto *ao : outputs)
 		ao->LockRelease();
 
-	if (pipe != nullptr) {
-		pipe->Clear();
-		delete pipe;
-		pipe = nullptr;
-	}
+	delete pipe;
+	pipe = nullptr;
 
 	input_audio_format.Clear();
 

src/player/Thread.cxx

@@ -169,14 +169,9 @@ private:
 		xfade_state = CrossFadeState::UNKNOWN;
 	}
 
-	void ClearAndDeletePipe() noexcept {
-		pipe->Clear();
-		delete pipe;
-	}
-
 	void ClearAndReplacePipe(MusicPipe *_pipe) noexcept {
 		ResetCrossFade();
-		ClearAndDeletePipe();
+		delete pipe;
 		pipe = _pipe;
 	}
 
@@ -1070,7 +1065,7 @@ Player::Run() noexcept
 	CancelPendingSeek();
 	StopDecoder();
 
-	ClearAndDeletePipe();
+	delete pipe;
 
 	cross_fade_tag.reset();