Add explicit

src/transcoder/transcoderoptionsspeex.h

@@ -31,13 +31,13 @@ class Ui_TranscoderOptionsSpeex;
 
 class TranscoderOptionsSpeex : public TranscoderOptionsInterface {
  public:
-  TranscoderOptionsSpeex(QWidget *parent = nullptr);
+  explicit TranscoderOptionsSpeex(QWidget *parent = nullptr);
   ~TranscoderOptionsSpeex();
 
   void Load();
   void Save();
 
-private:
+ private:
   static const char *kSettingsGroup;
 
   Ui_TranscoderOptionsSpeex *ui_;