FIX: Overwrite init function for legacy plugins

Legacy plugins have to skip the init procedure as they don't work that
way. In order to achieve that, they have to override the init function
and basically turn this into a (more or less= no-opt.

src/mumble/LegacyPlugin.cpp

@@ -119,6 +119,18 @@ void LegacyPlugin::resolveFunctionPointers() {
 	}
 }
 
+mumble_error_t LegacyPlugin::init() {
+	{
+		QWriteLocker lock(&m_pluginLock);
+
+		m_pluginIsLoaded = true;
+	}
+
+	// No-op as legacy plugins never have anything to initialize
+	// The only init function they care about is the one that inits positional audio
+	return STATUS_OK;
+}
+
 QString LegacyPlugin::getName() const {
 	PluginReadLocker lock(&m_pluginLock);
 

src/mumble/LegacyPlugin.h

@@ -63,6 +63,8 @@ class LegacyPlugin : public Plugin {
 	public:
 		virtual ~LegacyPlugin() override;
 
+		virtual mumble_error_t init() override;
+
 		// functions for direct plugin-interaction
 		virtual QString getName() const override;