Do not allow asan_symbolize.py to fall back to addr2line/atos.

Do not allow asan_symbolize.py to fall back to addr2line/atos.

For performance reasons we want to stick to llvm-symbolizer.
This also rolls the third-party asan_symbolize.py to r231492.

BUG=415179
TBR=glider@chromium.org
NOTRY=true

Committed: https://crrev.com/2ee9a8ae1e39433fc8df07c27256963715747bbb
Cr-Commit-Position: refs/heads/master@{#319460}

[earthdok, 2015-03-06 17:12:00]

The CQ bit was checked by earthdok@chromium.org

[commit-bot: I haz the power, 2015-03-06 17:12:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/983083004/1

[commit-bot: I haz the power, 2015-03-06 17:13:30]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-06 17:14:09]

Patchset 1 (id:??) landed as
https://crrev.com/2ee9a8ae1e39433fc8df07c27256963715747bbb
Cr-Commit-Position: refs/heads/master@{#319460}

[Alexander Potapenko, 2015-03-10 11:14:00]

On 2015/03/06 17:14:09, I haz the power (commit-bot) wrote:
> Patchset 1 (id:??) landed as
> https://crrev.com/2ee9a8ae1e39433fc8df07c27256963715747bbb
> Cr-Commit-Position: refs/heads/master@{#319460}

LGTM

[earthdok, 2015-03-17 19:17:01]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1017793002/ by earthdok@chromium.org.

The reason for reverting is: Turns out the fall back to addr2line happens
routinely. We need to fix that before proceeding with this change..