Revert of Pass -Oz flag to Clang when targeting Android.

Revert of Pass -Oz flag to Clang when targeting Android. (patchset #2 id:20001 of https://codereview.chromium.org/1103393002/)

Reason for revert:
Causes a build failure with -Dcomponent=shared_library

Original issue's description:
> Pass -Oz flag to Clang when targeting Android.
>
> The -Oz flag enables more aggressive size optimizations. Shrinks the
> libchromeshell.so DSO by around 2.5MB.
>
> BUG=481675
> R=thakis@chromium.org
>
> Committed: https://crrev.com/2433e6ab2206fad3bc5954fd61e9d4785ccab108
> Cr-Commit-Position: refs/heads/master@{#327183}

TBR=thakis@chromium.org,pcc@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=481675
Committed: https://crrev.com/eddc3cebcf7e727968611c314d34593f7bb1a97d
Cr-Commit-Position: refs/heads/master@{#327326}

[pcc, 2015-04-28 18:09:03]

Created Revert of Pass -Oz flag to Clang when targeting Android.

[commit-bot: I haz the power, 2015-04-28 18:09:57]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109203002/1

[commit-bot: I haz the power, 2015-04-28 18:09:57]

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

[commit-bot: I haz the power, 2015-04-28 18:09:58]

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,
_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, 2015-04-28 18:10:26]

lgtm

[Nico, 2015-04-28 18:10:30]

The CQ bit was checked by thakis@chromium.org

[commit-bot: I haz the power, 2015-04-28 18:11:05]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1109203002/1

[commit-bot: I haz the power, 2015-04-28 18:12:56]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-04-28 18:13:41]

Patchset 1 (id:??) landed as
https://crrev.com/eddc3cebcf7e727968611c314d34593f7bb1a97d
Cr-Commit-Position: refs/heads/master@{#327326}