Use anonymous namespace for constants

src/radios/radiomodel.cpp

@@ -39,7 +39,9 @@
 #include "radiomimedata.h"
 #include "radiochannel.h"
 
-const int RadioModel::kTreeIconSize = 22;
+namespace {
+constexpr int kTreeIconSize = 22;
+}
 
 RadioModel::RadioModel(Application *app, QObject *parent)
     : SimpleTreeModel<RadioItem>(new RadioItem(this), parent),

src/radios/radiomodel.h

@@ -86,7 +86,6 @@ class RadioModel : public SimpleTreeModel<RadioItem> {
   void AlbumCoverLoaded(const quint64 id, const AlbumCoverLoaderResult &result);
 
  private:
-  static const int kTreeIconSize;
   using ItemAndCacheKey = QPair<RadioItem*, QString>;
 
   Application *app_;