Use symlinking for dependency on libvpx
Use symlinking for dependency on libvpx

As opposed to in-source git-clone.

PiperOrigin-RevId: 344525899

google/ExoPlayer,amzn/exoplayer-amazon-port,ened/ExoPlayer,ened/ExoPlayer,amzn/exoplayer-amazon-port,androidx/media,google/ExoPlayer,androidx/media,amzn/exoplayer-amazon-port,google/ExoPlayer,androidx/media,ened/ExoPlayer