MIPS: Fix compile error for unitialized variable in simulator.

MIPS: Fix compile error for unitialized variable in simulator.

We see this error using GCC 4.8.2.

R=michael_dawson@ca.ibm.com
BUG=

Committed: https://crrev.com/ab3caa732719e06f075fd8fabf3c303df5ed9550
Cr-Commit-Position: refs/heads/master@{#28844}

[MTBrandyberry, 2015-05-28 17:08:36]

mbrandy@us.ibm.com changed reviewers:
+ plind44@gmail.com

[MTBrandyberry, 2015-05-28 17:08:56]

PTAL

[MTBrandyberry, 2015-05-28 17:16:05]

mbrandy@us.ibm.com changed reviewers:
+ akos.palfi@imgtec.com, balazs.kilvady@imgtec.com,
dusan.milosavljevic@imgtec.com, gergely.kis@imgtec.com, paul.lind@imgtec.com
- plind44@gmail.com

[paul.l..., 2015-06-08 17:18:14]

LGTM. Sorry for the delay, I was out of office when this came in and we dropped
the ball on getting this reviewed. Thanks for the change!

[MTBrandyberry, 2015-06-08 17:20:24]

The CQ bit was checked by mbrandy@us.ibm.com

[commit-bot: I haz the power, 2015-06-08 17:20:51]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1153213003/1

[commit-bot: I haz the power, 2015-06-08 18:17:11]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-06-08 18:17:25]

Patchset 1 (id:??) landed as
https://crrev.com/ab3caa732719e06f075fd8fabf3c303df5ed9550
Cr-Commit-Position: refs/heads/master@{#28844}