Fixing all of problems found by vc++ /analyze in GCM code

Fixing all of problems found by vc++ /analyze in GCM code

There was only a minor (harmless) case of variable shadowing.

BUG=427616
R=zea@chromium.org

Committed: https://crrev.com/3e021981ccc2be8de7443ff1a18439551b22ea75
Cr-Commit-Position: refs/heads/master@{#303338}

[fgorski, 2014-11-07 23:43:23]

fgorski@chromium.org changed reviewers:
+ zea@chromium.org
- zea@google.com

[brucedawson, 2014-11-07 23:45:31]

brucedawson@chromium.org changed reviewers:
+ brucedawson@chromium.org

[brucedawson, 2014-11-07 23:45:31]

lgtm

[Nicolas Zea, 2014-11-07 23:45:57]

lgtm

[fgorski, 2014-11-07 23:48:17]

The CQ bit was checked by fgorski@chromium.org

[commit-bot: I haz the power, 2014-11-07 23:50:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/713573003/1

[commit-bot: I haz the power, 2014-11-08 00:36:50]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-11-08 00:37:24]

Patchset 1 (id:??) landed as
https://crrev.com/3e021981ccc2be8de7443ff1a18439551b22ea75
Cr-Commit-Position: refs/heads/master@{#303338}

[matthewyuan, 2014-11-08 22:27:47]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/712793003/ by matthewyuan@chromium.org.

The reason for reverting is: Reverting since it's causing a crash on canary..