Handle Mozilla license blocks in the GN header checker.

Handle Mozilla license blocks in the GN header checker.

The include iterator doesn't handle real C preprocessor. Mozilla license blocks
use C-style comments with *'s along the left, and are long enough that the
header checker gives up.

This patch doesn't fix the general comment issue, different types of comments
can still confuse us, but Mozilla license blocks in particular are now handled.

BUG=543850
Committed: https://crrev.com/a2d721a90e955ee4fad4584c150e4aaca42e94d7
Cr-Commit-Position: refs/heads/master@{#354454}

[brettw, 2015-10-15 22:17:53]

brettw@chromium.org changed reviewers:
+ dpranke@chromium.org

[brettw, 2015-10-15 22:17:56]

The CQ bit was checked by brettw@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2015-10-15 22:18:33]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1411573002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1411573002/1

[commit-bot: I haz the power, 2015-10-15 22:34:59]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-10-15 22:35:00]

Dry run: This issue passed the CQ dry run.

[Dirk Pranke, 2015-10-16 01:17:14]

lgtm

[brettw, 2015-10-16 05:29:39]

The CQ bit was checked by brettw@chromium.org

[commit-bot: I haz the power, 2015-10-16 05:29:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1411573002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1411573002/1

[commit-bot: I haz the power, 2015-10-16 05:34:34]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-10-16 05:35:14]

Patchset 1 (id:??) landed as
https://crrev.com/a2d721a90e955ee4fad4584c150e4aaca42e94d7
Cr-Commit-Position: refs/heads/master@{#354454}