Manually cherry-picked commits:
ceef0583 libvpx->libaom part2
3d26d916 libvpx -> libaom
cfea7dd7 vp10/ -> av1/
3a8eff73 Fix a build issue for a test
bf4202ed Rename vpx to aom

Change-Id: I1b0eb5a40796e3aaf41c58984b4229a439a597dc