Fixed invalid references left from
the copied gyp_webrtc.

This CL will also add svn:ignore on a
bunch of directories to speed up builds
(less unnecessary delete + redownload).

It also adds the executable bit to
gyp_libyuv.

R=fbarchard@google.com

Review URL: https://webrtc-codereview.appspot.com/10889004

git-svn-id: http://libyuv.googlecode.com/svn/trunk@992 16f28f9a-4ce2-e073-06de-1de4eb20be90