Removes a double comment indicator from a copyright line. This can
break scripts that parse files to extract copyright and license
information.

Bug: None
Change-Id: I891d865020b64a4ae3dbe9dee369471e3d0368bf
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2516206Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>