Add return statement to LinuxCapabilityToKernelValue.

Add return statement to LinuxCapabilityToKernelValue.

The return statement should never be reached due to the LOG(FATAL), but
some compilers seem to think that it is possible to reach the end of
this function.

TBR=jln@chromium.org

Committed: https://crrev.com/eba228e0f27bef5170764bc2f8a9b7f96e389446
Cr-Commit-Position: refs/heads/master@{#320895}

[rickyz (no longer on Chrome), 2015-03-17 09:56:57]

rickyz@chromium.org changed reviewers:
+ ginkage@chromium.org, jln@chromium.org

[rickyz (no longer on Chrome), 2015-03-17 11:32:08]

The CQ bit was checked by rickyz@chromium.org

[commit-bot: I haz the power, 2015-03-17 11:32:24]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1017623003/1

[commit-bot: I haz the power, 2015-03-17 11:35:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-17 11:36:21]

Patchset 1 (id:??) landed as
https://crrev.com/eba228e0f27bef5170764bc2f8a9b7f96e389446
Cr-Commit-Position: refs/heads/master@{#320895}

[jln (very slow on Chromium), 2015-03-17 19:17:19]

lgtm, thanks