player, decoder, output: wrap MusicPipe in std::shared_ptr/std::unique_ptr

src/output/MultipleOutputs.cxx

@@ -230,7 +230,7 @@ MultipleOutputs::Open(const AudioFormat audio_format)
 	assert(pipe == nullptr || pipe->CheckFormat(audio_format));
 
 	if (pipe == nullptr)
-		pipe = new MusicPipe();
+		pipe = std::make_unique<MusicPipe>();
 	else
 		/* if the pipe hasn't been cleared, the the audio
 		   format must not have changed */
@@ -402,8 +402,7 @@ MultipleOutputs::Close() noexcept
 	for (auto *ao : outputs)
 		ao->LockCloseWait();
 
-	delete pipe;
-	pipe = nullptr;
+	pipe.reset();
 
 	input_audio_format.Clear();
 
@@ -416,8 +415,7 @@ MultipleOutputs::Release() noexcept
 	for (auto *ao : outputs)
 		ao->LockRelease();
 
-	delete pipe;
-	pipe = nullptr;
+	pipe.reset();
 
 	input_audio_format.Clear();
 

src/output/MultipleOutputs.hxx

@@ -55,7 +55,7 @@ class MultipleOutputs final : public PlayerOutputs {
 	 * The #MusicPipe object which feeds all audio outputs.  It is
 	 * filled by Play().
 	 */
-	MusicPipe *pipe = nullptr;
+	std::unique_ptr<MusicPipe> pipe;
 
 	/**
 	 * The "elapsed_time" stamp of the most recently finished