Clang update.py: enable debug info for ToT builds

Clang update.py: enable debug info for ToT builds

This should give us better stack traces when Clang crashes, which is
useful when doing ToT builds, whose purpose is to catch Clang regressions
early.

BUG=none

Committed: https://crrev.com/c58e45deb3bbb26184bb6b034b785fbfec89668e
Cr-Commit-Position: refs/heads/master@{#409802}

[hans, 2016-08-04 02:48:40]

hans@chromium.org changed reviewers:
+ rnk@chromium.org, thakis@chromium.org

[hans, 2016-08-04 02:48:41]

Reid mentioned this afternoon that it would be nice if our Clang bots provided
better stack traces.

I don't think we'd want to ship debug info in the clang package, but for the
tip-of-tree bots, it makes a lot of sense. The only down-side is slightly longer
build times.

What do you think?

[Nico, 2016-08-04 04:01:59]

Lgtm

Let's keep an eye on cycle time. Hopefully tot bots will still test what we ship
enough that we don't meaningfully lose coverage due to this.

[hans, 2016-08-04 15:24:57]

The CQ bit was checked by hans@chromium.org

[commit-bot: I haz the power, 2016-08-04 15:25:16]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-04 16:31:02]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-04 16:34:00]

Description was changed from

==========
Clang update.py: enable debug info for ToT builds

This should give us better stack traces when Clang crashes, which is
useful when doing ToT builds, whose purpose is to catch Clang regressions
early.

BUG=none
==========

to

==========
Clang update.py: enable debug info for ToT builds

This should give us better stack traces when Clang crashes, which is
useful when doing ToT builds, whose purpose is to catch Clang regressions
early.

BUG=none

Committed: https://crrev.com/c58e45deb3bbb26184bb6b034b785fbfec89668e
Cr-Commit-Position: refs/heads/master@{#409802}
==========

[commit-bot: I haz the power, 2016-08-04 16:34:01]

Patchset 1 (id:??) landed as
https://crrev.com/c58e45deb3bbb26184bb6b034b785fbfec89668e
Cr-Commit-Position: refs/heads/master@{#409802}

[Nico, 2016-08-04 20:43:16]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/2210383003/ by thakis@chromium.org.

The reason for reverting is: Speculative. clang binaries started failing without
any message (e.g.
https://build.chromium.org/p/chromium.fyi/builders/CrWinAsanCov/builds/2740/s...).
I don't see how this change could cause that, but it's in the blame list of each
of the win bots where this fails, non-win bots are fine, and this is the only
thing I see that is vaguely related..