allegro5: take image region into account for NK_COMMAND_IMAGE

demo/allegro5/nuklear_allegro5.h

@@ -324,7 +324,10 @@ nk_allegro5_render()
         } break;
         case NK_COMMAND_IMAGE: {
             const struct nk_command_image *i = (const struct nk_command_image *)cmd;
-            al_draw_bitmap_region(i->img.handle.ptr, 0, 0, i->w, i->h, i->x, i->y, 0);
+            al_draw_scaled_bitmap(i->img.handle.ptr,
+                                  i->img.region[0], i->img.region[1],
+                                  i->img.region[2], i->img.region[3],
+                                  i->x, i->y, i->w, i->h, 0);
         } break;
         case NK_COMMAND_RECT_MULTI_COLOR:
         default: break;