Port folder renaming changes from AOM

Manually cherry-picked commits:
ceef058 libvpx->libaom part2
3d26d91 libvpx -> libaom
cfea7dd vp10/ -> av1/
3a8eff7 Fix a build issue for a test
bf4202e Rename vpx to aom

Change-Id: I1b0eb5a40796e3aaf41c58984b4229a439a597dc
diff --git a/.gitignore b/.gitignore
index 8c57982..f6bf5a9 100644
--- a/.gitignore
+++ b/.gitignore
@@ -45,8 +45,8 @@
 /ivfdec.dox
 /ivfenc
 /ivfenc.dox
-/libvpx.so*
-/libvpx.ver
+/libaom.so*
+/libaom.ver
 /samples.dox
 /test_intra_pred_speed
 /test_libvpx