fix cc_unittests gcc build

fix cc_unittests gcc build

Avoid -Wparentheses errors in gcc builds.
Followup to https://codereview.chromium.org/595593002

BUG=159225

[Mostyn Bramley-Moore, 2015-02-27 21:28:15]

mostynb@opera.com changed reviewers:
+ awoloszyn@chromium.org, danakj@chromium.org

[Mostyn Bramley-Moore, 2015-02-27 21:28:16]

@danakj: can you PTAL at this tiny fixup?

Without this, gcc builds fail with errors like the following:

../../cc/output/renderer_pixeltest.cc:818:62: error: suggest parentheses around
'+' in operand of '&' [-Werror=parentheses]

[danakj, 2015-02-27 21:36:08]

LGTM

[Mostyn Bramley-Moore, 2015-02-27 21:38:35]

The CQ bit was checked by mostynb@opera.com

[commit-bot: I haz the power, 2015-02-27 21:39:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/962363002/1

[Mostyn Bramley-Moore, 2015-02-27 22:26:43]

The CQ bit was unchecked by mostynb@opera.com

[Mostyn Bramley-Moore, 2015-02-27 22:28:26]

Un-queued this, since https://codereview.chromium.org/960893004 reverted the
original change.

@awoloszyn: can you roll this fixup into your branch (which I assume you will
re-submit)?

[awoloszyn, 2015-02-27 22:37:13]

On 2015/02/27 22:28:26, Mostyn Bramley-Moore wrote:
> Un-queued this, since https://codereview.chromium.org/960893004 reverted the
> original change.
> 
> @awoloszyn: can you roll this fixup into your branch (which I assume you will
> re-submit)?

Will do sorry about the churn.