Fix #132861: Proportional edit broken due to uninitialized transform data

The `td->center` value is used to compute proportional editing distances,
but initialization order was broken in 9d86fada which sets every center
to zero.

Pull Request: https://projects.blender.org/blender/blender/pulls/132913

source/blender/editors/transform/transform_convert_curves.cc

@@ -544,7 +544,7 @@ void curve_populate_trans_data_structs(
             center = point_positions[domain_i];
           }
           else {
-            center = td.iloc;
+            center = *elem;
           }
 
           copy_v3_v3(td.iloc, *elem);