clang-tidy: add explicit deleted constructors

Found with cppcoreguidelines-special-member-functions

Signed-off-by: Rosen Penev <rosenp@gmail.com>

src/output/plugins/ShoutOutputPlugin.cxx

@@ -51,6 +51,9 @@ struct ShoutOutput final : AudioOutput {
 	explicit ShoutOutput(const ConfigBlock &block);
 	~ShoutOutput() override;
 
+	ShoutOutput(const ShoutOutput &) = delete;
+	ShoutOutput &operator=(const ShoutOutput &) = delete;
+
 	static AudioOutput *Create(EventLoop &event_loop,
 				   const ConfigBlock &block);