Use fast_unwind_on_fatal=1 by default in ASan builds.

Use fast_unwind_on_fatal=1 by default in ASan builds.
This'll help us avoid crashes in the slow unwinder when unvinding through
V8-generated code.

BUG=422698
R=inferno@chromium.org
NOTRY=true

Committed: https://crrev.com/6744839e1f3d6c8abe49e685e9bfcb91c4abb154
Cr-Commit-Position: refs/heads/master@{#300780}

[Alexander Potapenko, 2014-10-22 22:18:44]

PTAL

[inferno, 2014-10-22 22:20:35]

lgtm

[Alexander Potapenko, 2014-10-22 22:22:22]

The CQ bit was checked by glider@chromium.org

[commit-bot: I haz the power, 2014-10-22 22:24:46]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/668343002/1

[commit-bot: I haz the power, 2014-10-22 22:26:15]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-22 22:26:55]

Patchset 1 (id:??) landed as
https://crrev.com/6744839e1f3d6c8abe49e685e9bfcb91c4abb154
Cr-Commit-Position: refs/heads/master@{#300780}

[Evgeniy Stepanov, 2014-10-22 22:26:56]

On 2014/10/22 22:26:15, I haz the power (commit-bot) wrote:
> Committed patchset #1 (id:1)

Do we want this for TSan as well?
Not for MSan, as that uses the V8 simulator.

[Alexander Potapenko, 2014-10-22 22:31:00]

On 2014/10/22 22:26:56, Evgeniy Stepanov wrote:
> On 2014/10/22 22:26:15, I haz the power (commit-bot) wrote:
> > Committed patchset #1 (id:1)
> 
> Do we want this for TSan as well?
> Not for MSan, as that uses the V8 simulator.

Nope. TSan uses shadow stack for unwinding.