Errrr Android ART is a VM and no you can't write games in C/C++ on Android. While technically it can be done it's pretty much impossible to get it off the ground and running because of the VM in place.

There is a website that lists the games people have created to try it successfully, they give links to couple of them which made it into the Android store and basically you can tell by all the feedback that the game won't load. You can try to run the games too and see if you're lucky, I wasn't....

Objective-C is very quite fast, several notches faster then Java apps