Added move constructor to plog_appender

src/capi.cpp

@@ -199,6 +199,11 @@ class plog_appender : public plog::IAppender {
 public:
 	plog_appender(rtcLogCallbackFunc cb = nullptr) { set_callback(cb); }
 
+	plog_appender(plog_appender &&appender) {
+		std::lock_guard lock(appender.callbackMutex);
+		std::exchange(appender.callback, callback);
+	}
+
 	void set_callback(rtcLogCallbackFunc cb) {
 		std::lock_guard lock(callbackMutex);
 		callback = cb;