output/pulse: convert to class

src/output/plugins/PulseOutputPlugin.cxx

@@ -42,7 +42,9 @@
 
 #define MPD_PULSE_NAME "Music Player Daemon"
 
-struct PulseOutput {
+class PulseOutput {
+	friend struct AudioOutputWrapper<PulseOutput>;
+
 	AudioOutput base;
 
 	const char *name;

src/output/plugins/PulseOutputPlugin.hxx

@@ -20,7 +20,7 @@
 #ifndef MPD_PULSE_OUTPUT_PLUGIN_HXX
 #define MPD_PULSE_OUTPUT_PLUGIN_HXX
 
-struct PulseOutput;
+class PulseOutput;
 class PulseMixer;
 struct pa_cvolume;
 class Error;