Qt: deprecation warnings, again

Check Qt version for the QFontMetrics::width vs horizontalAdvance.
Of course can't just #define horizontalAdvance to width, that would
be too easy ...

win/Qt/qt_menu.h

@@ -24,7 +24,7 @@ public:
 	int width = 0;
 	QFontMetrics fm(font());
 	for (int i = 0; i < count(); i++) {
-	    int lwidth = fm.horizontalAdvance(item(i)->text());
+	    int lwidth = fm.QFM_WIDTH(item(i)->text());
 	    width = std::max(width, lwidth);
 	}
 	return width;