Switch to my forks for compatibility with htc bravo:
- Forked ART, BUILD
- Use PurityROM's bionic for increased performance
- DIsmiss older toolchains (obsolete because we use GCC Linaro v4.9 / Andrpoid-eabi v4.8)

Change-Id: Ic0c641dbc693e1bf36c91741f8146cb3ba96c2e9