gn: Add missing -Wexit-time-destructors

gn: Add missing -Wexit-time-destructors on base

TBR=brettw@chromium.org
BUG=335824
Committed: https://crrev.com/9126e8dba3eddf1d3c21378263e4ed47e9a79487
Cr-Commit-Position: refs/heads/master@{#294263}

[scottmg, 2014-09-10 20:04:54]

The CQ bit was checked by scottmg@chromium.org

[commit-bot: I haz the power, 2014-09-10 20:17:56]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/scottmg@chromium.org/560143002/1

[commit-bot: I haz the power, 2014-09-10 20:17:57]

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

[commit-bot: I haz the power, 2014-09-10 20:17:58]

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 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.

[scottmg, 2014-09-10 22:46:02]

The CQ bit was checked by scottmg@chromium.org

[commit-bot: I haz the power, 2014-09-10 22:51:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patchset/560143002/1

[brettw, 2014-09-10 22:52:51]

lgtm

[commit-bot: I haz the power, 2014-09-10 23:53:55]

Committed patchset #1 (id:1) as 4c4f0ba8de356f971511374df2e68f71d72fe32c

[commit-bot: I haz the power, 2014-09-11 00:09:10]

Patchset 1 (id:??) landed as
https://crrev.com/9126e8dba3eddf1d3c21378263e4ed47e9a79487
Cr-Commit-Position: refs/heads/master@{#294263}