Silence git-hooks/pre-commit in the absence of .gitmodules.

Silence git-hooks/pre-commit in the absence of .gitmodules.

Other projects use depot_tools (which pulls in this hook) and chromium's build/
(where the hook lives) but don't use git modules (e.g. webrtc).

TBR=szager@chromium.org

Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=257470

[Ami GONE FROM CHROMIUM, 2014-03-17 16:38:43]

TBRing on the strength of the LGTM given in
https://codereview.chromium.org/192833005/

[Ami GONE FROM CHROMIUM, 2014-03-17 16:38:48]

The CQ bit was checked by fischman@chromium.org

[commit-bot: I haz the power, 2014-03-17 16:38:57]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/fischman@chromium.org/196413021/1

[commit-bot: I haz the power, 2014-03-17 18:36:41]

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

[commit-bot: I haz the power, 2014-03-17 18:36:43]

Commit queue rejected this change because the description was changed
between the time the change entered the commit queue and the time it
was ready to commit. You can safely check the commit box again.

[Ami GONE FROM CHROMIUM, 2014-03-17 18:49:07]

The CQ bit was checked by fischman@chromium.org

[commit-bot: I haz the power, 2014-03-17 18:49:55]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/fischman@chromium.org/196413021/1

[commit-bot: I haz the power, 2014-03-17 18:50:48]

Change committed as 257470

[davve, 2014-03-19 08:52:06]

On 2014/03/17 18:50:48, I haz the power (commit-bot) wrote:
> Change committed as 257470

FYI, I get:

build/git-hooks/pre-commit: 26: build/git-hooks/pre-commit: [[: not found

[[ a bash:ism, AFAIK. My sh is dash (on Debian). Submitted
https://codereview.chromium.org/203463010/ to address.