Revert of Disable -Wl,-z,defs on mipsel to suppress ffmpeg error

Revert of Disable -Wl,-z,defs on mipsel to suppress ffmpeg error (patchset #2 id:20001 of https://codereview.chromium.org/864193002/)

Reason for revert:
ffmpeg issue was fixed here: https://gerrit.chromium.org/gerrit/#/c/73566/ which was rolled into chromium here: https://crrev.com/313130

Original issue's description:
> Disable -Wl,-z,defs on mipsel to suppress ffmpeg error
> 
> The ffmpeg build on mips is broken which manifests in build errors when
> z,defs is specified. The owners of this build would like the compile
> time error to be suppressed for now while they work on a proper fix.
> 
> BUG=450771, 371125
> 
> Committed: https://crrev.com/9267528ad62c796f30c9f51f398fbfa29f0232a1
> Cr-Commit-Position: refs/heads/master@{#312557}

TBR=thakis@chromium.org,zork@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=450771, 371125

[jamesr, 2015-01-27 20:26:41]

Created Revert of Disable -Wl,-z,defs on mipsel to suppress ffmpeg error

[commit-bot: I haz the power, 2015-01-27 20:26:49]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/873313007/1

[commit-bot: I haz the power, 2015-01-27 20:27:33]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-01-27 20:27:34]

Failed to apply patch for build/config/compiler/BUILD.gn:
While running git apply --index -3 -p1;
  error: patch failed: build/config/compiler/BUILD.gn:302
  error: repository lacks the necessary blob to fall back on 3-way merge.
  error: build/config/compiler/BUILD.gn: patch does not apply

Patch:       build/config/compiler/BUILD.gn
Index: build/config/compiler/BUILD.gn
diff --git a/build/config/compiler/BUILD.gn b/build/config/compiler/BUILD.gn
index
a1d68e97b40004ce2d40a14cf9f241e83b1af135..d929781d2564ee22a1200014167dd356ecaf7525
100644
--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -302,10 +302,7 @@
       "-Wl,-z,now",
       "-Wl,-z,relro",
     ]
-
-    # TODO(zork): The mipsel build is broken in ffmpeg, guard this flag for now
-    # to hide the breakage. https://crbug.com/450771
-    if (!using_sanitizer && cpu_arch != "mipsel") {
+    if (!using_sanitizer) {
       ldflags += [ "-Wl,-z,defs" ]
     }
   }

[commit-bot: I haz the power, 2015-01-27 20:27:58]

The CQ bit was unchecked by commit-bot@chromium.org

[Nico, 2015-01-27 20:28:11]

Already done in https://codereview.chromium.org/878603005

[jamesr, 2015-01-27 20:30:05]

Ah, cool.