Android TV Support

Based on initial testing, PPSSPP runs fine on ADT-1 hardware running the latest developer preview of Android TV. 

![s4](https://cloud.githubusercontent.com/assets/1561087/3961834/ffa79a18-275c-11e4-8fab-de5d3f9fbbfc.png)
![s3](https://cloud.githubusercontent.com/assets/1561087/3961835/0509d25a-275d-11e4-8937-77f64b8fd698.png)

With these commits, PPSSPP shows up as an app under Leanback, Android TV's media-focused launcher.

![s2](https://cloud.githubusercontent.com/assets/1561087/3961848/2a39b982-275d-11e4-81e7-be9abc5d6928.png)