fix: optimization: PVS-Studio warning V836

Expression's value is copied at variable declaration.
The variable is never modified. Consider declaring it as a reference.

Changed variables to be a reference to avoid unnecessary copy.

Reported by: PVS-Studio

Signed-off-by: Vyacheslav Ivanov <islavaivanov76@gmail.com>

src/graphics/ui/gui_xml.cpp

@@ -203,7 +203,7 @@ static void _readPanel(UiXmlReader& reader, const xml::xmlelement& element, Pane
         panel.setMaxLength(element->attr("max-length").asInt());
     }
     if (element->has("orientation")) {
-        auto oname = element->attr("orientation").getText();
+        const auto &oname = element->attr("orientation").getText();
         if (oname == "horizontal") {
             panel.setOrientation(Orientation::horizontal);
         }