correctly draw non-filled rectangle for GDI demo

demo/gdi/nuklear_gdi.h

@@ -170,6 +170,13 @@ nk_gdi_stroke_rect(HDC dc, short x, short y, unsigned short w,
     unsigned short h, unsigned short r, unsigned short line_thickness, struct nk_color col)
 {
     COLORREF color = convert_color(col);
+    POINT points[] = {
+        { x, y },
+        { x + w, y },
+        { x + w, y + h },
+        { x, y + h },
+        { x, y },
+    };
 
     HPEN pen = NULL;
     if (line_thickness == 1) {
@@ -179,12 +186,7 @@ nk_gdi_stroke_rect(HDC dc, short x, short y, unsigned short w,
         SelectObject(dc, pen);
     }
 
-    SetDCBrushColor(dc, OPAQUE);
-    if (r == 0) {
-        Rectangle(dc, x, y, x + w, y + h);
-    } else {
-        RoundRect(dc, x, y, x + w, y + h, r, r);
-    }
+    Polyline(dc, points, 5);
 
     if (pen) {
         SelectObject(dc, GetStockObject(DC_PEN));