Fix rss icon too large in rss settings dialog

Give a name to the rss icon (in .ui file)
Add helper function: Utils::Misc::largeIconSize()
Group functions under the same #ifdef

src/base/utils/misc.h

@@ -69,11 +69,6 @@ namespace Utils
 
         void shutdownComputer(const ShutdownDialogAction &action);
 
-#ifndef DISABLE_GUI
-        // Get screen center
-        QPoint screenCenter(QWidget *win);
-        QSize smallIconSize();
-#endif
         QString osName();
         QString boostVersionString();
         QString libtorrentVersionString();
@@ -107,6 +102,10 @@ namespace Utils
 #ifndef DISABLE_GUI
         void openPath(const QString& absolutePath);
         void openFolderSelect(const QString& absolutePath);
+
+        QPoint screenCenter(QWidget *win);
+        QSize smallIconSize();
+        QSize largeIconSize();
 #endif
 
 #ifdef Q_OS_WIN