Roll ffmpeg.

This brings in linux-noasm configs for ChromiumOS and ChromeOS.

BUG=340376
TBR=wolenetz@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/650083002

Cr-Commit-Position: refs/heads/master@{#299286}

DEPS

@@ -220,7 +220,7 @@ deps = {
    Var('chromium_git') + '/chromium/deps/libvpx.git' + '@' +  Var('libvpx_revision'),
 
   'src/third_party/ffmpeg':
-   Var('chromium_git') + '/chromium/third_party/ffmpeg.git' + '@' + 'a6b106cb586f6996add9af6eb15dfb01488f587f',
+   Var('chromium_git') + '/chromium/third_party/ffmpeg.git' + '@' + 'eca71c39e228bcf4559ef7cfc249376d7f0dee61',
 
   'src/third_party/libjingle/source/talk':
     Var('chromium_git') + '/external/webrtc/trunk/talk.git' + '@' + '1f6d92bb25f108ee5ec418811d95ca757bf228f9',