Why won't the small screws on the outside cover come out?

One of the screws at the bottom of my iPhone won't come out. Basically the head has been distorted to the point no screw driver will bite into it enough to remove it from the body of the iPhone so I can do a screen replacement. It also appears wedged in the hole as if it was cross threaded when it came from Apple or else it was jarred making it crooked from being dropped.

Anyone have any ideas?

I considered bore-ing through the screw with a small drill bit. Similar idea to tapping when you break a bolt or something off on a car.