allegro5: correctly handle zero region in NK_COMMAND_IMAGE

demo/allegro5/nuklear_allegro5.h

@@ -324,9 +324,11 @@ nk_allegro5_render()
         } break;
         case NK_COMMAND_IMAGE: {
             const struct nk_command_image *i = (const struct nk_command_image *)cmd;
+            nk_ushort w = i->img.region[2],
+                h = i->img.region[3];
             al_draw_scaled_bitmap(i->img.handle.ptr,
                                   i->img.region[0], i->img.region[1],
-                                  i->img.region[2], i->img.region[3],
+                                  w ? w : i->w, h ? h : i->h,
                                   i->x, i->y, i->w, i->h, 0);
         } break;
         case NK_COMMAND_RECT_MULTI_COLOR: