third_party/update_libs.sh: Enable libyuv and disable unit tests.

libyuv: Required for scaling decoder output when a vpx stream
        uses spatial resampling.
unit tests: We don't run them, and building them wastes time.

Change-Id: I106fcd3a523af5b1f5a46c7abc5c44411bfeb3b0
webmdshow: Update libvpx.

Update to v1.3.0-4763-g825e270, which is current HEAD with the main
purpose being to add libyuv support to webmdshow's libvpx build.

Change-Id: I6d65728f346867986b64cdefa45d78f683693ced
webmdshow: Fix EoLs (CRLF -> LF) in VP8 Decoder Filter.

Change-Id: I0217b26918dacfa90096e94b346d02dc7e556f78
Merge "webmdshow: Fix EoLs (CRLF -> LF) in VP8 Decoder Filter."
Merge "webmdshow: Update libvpx."