PPC64: Fix return value checks for generated regexp code.

PPC64: Fix return value checks for generated regexp code.

This fixes simulated debug-mode failures in the following tests:
  mjsunit/regexp-stack-overflow
  mjsunit/regress/regress-crbug-467047

R=mbrandy@us.ibm.com

BUG=

Committed: https://crrev.com/fab0f042e6630cea7c78b4d8d5058d610b05a526
Cr-Commit-Position: refs/heads/master@{#27500}

[michael_dawson, 2015-03-26 22:57:35]

Next PPC patch

[MTBrandyberry, 2015-03-27 00:55:33]

On 2015/03/26 22:57:35, michael_dawson wrote:
> Next PPC patch

lgtm

[michael_dawson, 2015-03-27 13:07:51]

The CQ bit was checked by michael_dawson@ca.ibm.com

[commit-bot: I haz the power, 2015-03-27 13:08:01]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1035003002/1

[commit-bot: I haz the power, 2015-03-27 13:30:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-03-27 13:30:51]

Patchset 1 (id:??) landed as
https://crrev.com/fab0f042e6630cea7c78b4d8d5058d610b05a526
Cr-Commit-Position: refs/heads/master@{#27500}