Fix for clang build warnings: undefined variables if !USE_UDEV.

Fix for clang build warnings: undefined variables if !USE_UDEV.

R=agoode@chromium.org,wolenetz@chromium.org
BUG=None

Committed: https://crrev.com/504b1da3fb365a0c59af25ba44dbeb998b764a5e
Cr-Commit-Position: refs/heads/master@{#321526}

[Adam Goode, 2015-03-20 00:09:37]

lgtm

[gunsch, 2015-03-20 00:14:29]

The CQ bit was checked by gunsch@chromium.org

[commit-bot: I haz the power, 2015-03-20 00:14:47]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1023893002/1

[commit-bot: I haz the power, 2015-03-20 00:14:49]

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

[commit-bot: I haz the power, 2015-03-20 00:14:49]

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,
_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.

[gunsch, 2015-03-20 01:29:17]

gunsch@chromium.org changed reviewers:
+ toyoshim@chromium.org

[gunsch, 2015-03-20 01:29:29]

+toyoshim: can you take a quick look for OWNERS?

[Takashi Toyoshima, 2015-03-20 05:52:24]

lgtm

[Takashi Toyoshima, 2015-03-20 05:52:31]

The CQ bit was checked by toyoshim@chromium.org

[commit-bot: I haz the power, 2015-03-20 05:52:43]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1023893002/1

[commit-bot: I haz the power, 2015-03-20 06:32:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-20 06:33:05]

Patchset 1 (id:??) landed as
https://crrev.com/504b1da3fb365a0c59af25ba44dbeb998b764a5e
Cr-Commit-Position: refs/heads/master@{#321526}