output/Finish: fold internal function into FinishDestroy()

src/output/Finish.cxx

@@ -23,8 +23,6 @@
 #include "mixer/MixerControl.hxx"
 #include "filter/FilterInternal.hxx"
 
-#include <assert.h>
-
 AudioOutput::~AudioOutput()
 {
 	if (mixer != nullptr)
@@ -36,12 +34,6 @@ AudioOutput::~AudioOutput()
 }
 
 void
-audio_output_free(AudioOutput *ao) noexcept
-{
-	ao_plugin_finish(ao);
-}
-
-void
 AudioOutput::BeginDestroy() noexcept
 {
 	if (mixer != nullptr)
@@ -51,5 +43,5 @@ AudioOutput::BeginDestroy() noexcept
 void
 AudioOutput::FinishDestroy() noexcept
 {
-	audio_output_free(this);
+	ao_plugin_finish(this);
 }

src/output/Internal.hxx

@@ -187,7 +187,4 @@ audio_output_new(EventLoop &event_loop,
 		 const ConfigBlock &block,
 		 MixerListener &mixer_listener);
 
-void
-audio_output_free(AudioOutput *ao) noexcept;
-
 #endif