Roll src/third_party/ffmpeg

Roll src/third_party/ffmpeg

New changes in ffmpeg repo add a flag to build ffmpeg as a
shared library to help out the linux packagers. See
discussion here:
https://groups.google.com/a/chromium.org/forum/#!msg/chromium-packagers/R5rcZXWxBEQ/B6k0zzmJbvcJ

Summary of changes available at:
https://chromium-review.googlesource.com/#/c/281211/

BUG=none
TESTS=media_unittests && confirmed fix with linux packagers.

Committed: https://crrev.com/c1cab0163fca4dad68c05c7f14567051730f27da
Cr-Commit-Position: refs/heads/master@{#335967}

[chcunningham, 2015-06-23 19:50:00]

The CQ bit was checked by chcunningham@chromium.org

[chcunningham, 2015-06-23 19:50:00]

The CQ bit was unchecked by chcunningham@chromium.org

[chcunningham, 2015-06-23 22:32:18]

chcunningham@chromium.org changed reviewers:
+ dalecurtis@chromium.org, watk@chromium.org

[DaleCurtis, 2015-06-24 17:57:54]

lgtm

[chcunningham, 2015-06-24 17:59:00]

The CQ bit was checked by chcunningham@chromium.org

[commit-bot: I haz the power, 2015-06-24 18:00:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1198653005/20001

[commit-bot: I haz the power, 2015-06-24 19:03:37]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-24 19:04:40]

Patchset 2 (id:??) landed as
https://crrev.com/c1cab0163fca4dad68c05c7f14567051730f27da
Cr-Commit-Position: refs/heads/master@{#335967}