Reenable -Wl,-z,defs on mipsel

Reenable -Wl,-z,defs on mipsel

The flags were disabled to suppress a build error in ffmpeg.
The error should be fixed now:
https://crrev.com/a458f95e5718918a70506be2a33ea3be55e59024

BUG=450771, 371125
TEST=emerge-mipsel-o32-generic chromeos-chrome
cbuildbot --remote mipsel-o32-generic-tot-chromium-pfq-informational

Committed: https://crrev.com/4f79c115cae3f007a52eab70f614ab3c9b95f011
Cr-Commit-Position: refs/heads/master@{#313180}

[tbarzic, 2015-01-26 22:58:35]

tbarzic@chromium.org changed reviewers:
+ thakis@chromium.org

[tbarzic, 2015-01-26 22:58:36]

cros tryserver looks happy with this :)
(http://chromegw.corp.google.com/i/chromiumos.tryserver/builders/mipsel-o32-ge...)

[Nico, 2015-01-26 23:01:00]

awesome, lgtm. Thanks :-)

[tbarzic, 2015-01-26 23:01:30]

The CQ bit was checked by tbarzic@chromium.org

[commit-bot: I haz the power, 2015-01-26 23:02:25]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/878603005/20001

[commit-bot: I haz the power, 2015-01-27 00:38:56]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-01-27 00:40:33]

Patchset 2 (id:??) landed as
https://crrev.com/4f79c115cae3f007a52eab70f614ab3c9b95f011
Cr-Commit-Position: refs/heads/master@{#313180}