Revert of Enable FIXED_POINT and -O3 for Opus when building for ARM.

Revert of Enable FIXED_POINT and -O3 for Opus when building for ARM. (https://codereview.chromium.org/315673002/)

Reason for revert:
Media tests started failing consistently after this: http://build.chromium.org/p/chromium.memory.fyi/builders/Linux%20Tests%20%28tsan%29%281%29?numbuilds=200

It doesn't look super related, but the <() / >() change in common.gypi looks a bit suspicious, so revert this speculatively and see if it helps.

Original issue's description:
> - Enable FIXED_POINT for Opus when building for arm64. This yields:
>   ~21% speed up over floating point.
>   2.6% increase in executable size.
> - Also switched to late expansion of release_optimize in common.gypi (debug_optimize was already using it). This makes it possible to set optimization level via release_optimize in lower level targets.
> 
> - Enable -O3 for Opus when building form arm32/arm64. This yields:
>   arm32: Speed increase up to 21% (encode) and 5% (decode).
>   arm32: 2.8% increase in executable size.
>   arm32: Output is bit exact with the output when -Os is used.
>   arm64: Speed increase up to 18% (encode) and 25% (decode).
>   arm64: 7.4% increase in executable size.
>   arm64: Output is exact within one LSB (max difference is 2) with the arm32 output.
> 
> Measured using webrtc/audio_codec_speed_tests.
> 
> BUG=chromium:354539
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=277414

TBR=tlegrand1, Sergey Ulanov, Solis
NOTRY=true
NOTREECHECKS=true

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=279198

[Nico, 2014-06-23 22:08:50]

Created Revert of Enable FIXED_POINT and -O3 for Opus when building for ARM.

[commit-bot: I haz the power, 2014-06-23 22:11:16]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/thakis@chromium.org/349293006/1

[commit-bot: I haz the power, 2014-06-23 22:11:17]

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

[commit-bot: I haz the power, 2014-06-23 22:11:18]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[Nico, 2014-06-23 22:13:42]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2014-06-23 22:15:05]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/thakis@chromium.org/349293006/1

[commit-bot: I haz the power, 2014-06-23 22:20:23]

Change committed as 279198