Revert of Roll opus to opus-HEAD-66611f1.

Revert of Roll opus to opus-HEAD-66611f1. (patchset #3 id:40001 of https://codereview.chromium.org/865853005/)

Reason for revert:
This CL breaks WebRTC in Chrome since the new Opus version is not bit-exact with the previous version.

Original issue's description:
> Roll opus to opus-HEAD-66611f1.
>
> The third_party/opus/src CL is https://codereview.chromium.org/882843002.
>
> Support MIPS optimizations in opus.
>
> R=henrika@chromium.org,sergeyu@chromium.org
> BUG=452984
>
> Committed: https://crrev.com/ebbf54dafa1be134a4d45fc30c103388dfaa8ff0
> Cr-Commit-Position: refs/heads/master@{#313646}

TBR=sergeyu@chromium.org,tlegrand@chromium.org,wtc@chromium.org
BUG=452984
Committed: https://crrev.com/cd35af688438dfb0b31fff626cf0ff6ac52fd44f
Cr-Commit-Position: refs/heads/master@{#314322}

[henrika (OOO until Aug 14), 2015-02-03 09:19:51]

Created Revert of Roll opus to opus-HEAD-66611f1.

[commit-bot: I haz the power, 2015-02-03 09:20:33]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/899623002/1

[commit-bot: I haz the power, 2015-02-03 09:21:04]

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

[commit-bot: I haz the power, 2015-02-03 09:21:06]

Failed to apply patch for third_party/opus/BUILD.gn:
While running git apply --index -3 -p1;
  error: patch failed: third_party/opus/BUILD.gn:3
  Falling back to three-way merge...
  Applied patch to 'third_party/opus/BUILD.gn' with conflicts.
  U third_party/opus/BUILD.gn

Patch:       third_party/opus/BUILD.gn
Index: third_party/opus/BUILD.gn
diff --git a/third_party/opus/BUILD.gn b/third_party/opus/BUILD.gn
index
8f51d09ffd4bd6f8808bf4054fbcb919465b4795..2905a4922b30a1a882f4a379c2794ebb642b5932
100644
--- a/third_party/opus/BUILD.gn
+++ b/third_party/opus/BUILD.gn
@@ -3,19 +3,12 @@
 # found in the LICENSE file.
 
 import("//build/config/arm.gni")
-import("//build/config/mips.gni")
 
 # If fixed point implementation shall be used (otherwise float).
-# TODO(wtc): change "mipselx" to "mipsel" in this file when the compilation
-# errors in the MIPS optimizations are fixed.
-use_opus_fixed_point =
-    cpu_arch == "arm" || cpu_arch == "arm64" || cpu_arch == "mipselx"
+use_opus_fixed_point = cpu_arch == "arm" || cpu_arch == "arm64"
 
 # If ARM optimizations shall be used to accelerate performance.
 use_opus_arm_optimization = cpu_arch == "arm"
-
-# If MIPS optimizations shall be used to accelerate performance.
-use_opus_mips_optimization = cpu_arch == "mipselx"
 
 # If OPUS Run Time CPU Detections (RTCD) shall be used.
 # Based on the conditions in celt/arm/armcpu.c:
@@ -142,29 +135,6 @@
       ]
     }
   }
-
-  if (use_opus_mips_optimization) {
-    sources += [
-      "src/celt/mips/celt_mipsr1.h",
-      "src/celt/mips/fixed_generic_mipsr1.h",
-      "src/celt/mips/kiss_fft_mipsr1.h",
-      "src/celt/mips/mdct_mipsr1.h",
-      "src/celt/mips/pitch_mipsr1.h",
-      "src/celt/mips/vq_mipsr1.c",
-      "src/celt/mips/vq_mipsr1.h",
-      "src/silk/fixed/mips/noise_shape_analysis_FIX_mipsr1.h",
-      "src/silk/fixed/mips/prefilter_FIX_mipsr1.h",
-      "src/silk/fixed/mips/warped_autocorrelation_FIX_mipsr1.h",
-      "src/silk/mips/NSQ_del_dec_mipsr1.h",
-      "src/silk/mips/macros_mipsr1.h",
-      "src/silk/mips/sigproc_fix_mipsr1.h",
-    ]
-
-    defines += [
-      "MIPSr1_ASM",
-      "USE_ALLOCA",
-    ]
-  }
 }
 
 executable("opus_compare") {

[commit-bot: I haz the power, 2015-02-03 09:21:12]

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

[henrika (OOO until Aug 14), 2015-02-03 09:21:44]

The CQ bit was unchecked by henrika@chromium.org

[henrika (OOO until Aug 14), 2015-02-03 11:03:08]

The CQ bit was checked by henrika@chromium.org

[commit-bot: I haz the power, 2015-02-03 11:03:59]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/899623002/1

[commit-bot: I haz the power, 2015-02-03 12:56:48]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-02-03 12:57:51]

Patchset 1 (id:??) landed as
https://crrev.com/cd35af688438dfb0b31fff626cf0ff6ac52fd44f
Cr-Commit-Position: refs/heads/master@{#314322}