qtquick3dphysics: no configure summary; missing subconfig

At the top level, configure.json has

{
    "subconfigs": [
        "src/quick3dphysics"
    ]
}

and there's not another configure.json in src/quick3dphysics.

When configuring Qt, there is currently no output in the summary to indicate that I have successfully configured this module: the only confirmation is the lack of errors earlier when it's running config tests, and of course the module ends up building and working (yay, it's a fun one). I was surprised not to see a section like

Qt Quick 3D Physics:
  Something whatever .......................... yes

but I guess it's because there are no features to turn on or off? Maybe there should be, if some rarely-used features could be disabled to make it more efficient or smaller or something... but mostly just because it would be more satisfying to see some output there in the summary.