tests/evas: Enable evas 3d mesh test case again after the code got fixed.

The problem have been in the new evas block/unblock code which did not work
for evas 3d. Thanks to Bogdan for spotting it and raster for reverting the
3d part for now to keep the code working.

Fixes T2104

src/tests/evas/evas_test_mesh.c

@@ -132,5 +132,5 @@ END_TEST
 
 void evas_test_mesh(TCase *tc)
 {
-   //tcase_add_test(tc, evas_object_mesh_loader_saver);
+   tcase_add_test(tc, evas_object_mesh_loader_saver);
 }