Add missing copyright symbol

[fmarier]

Fixes brave/brave-browser#4990.

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Android
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that all lint errors/warnings are resolved (npm run lint)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protection-Mode
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

Open brave://settings/help and brave://version and confirm that the (C) symbol is present.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[fmarier]

CI is green except for httplib2 failure:

• https://staging.ci.brave.com/job/brave-browser-build-pr/job/francois-missing-copyright-symbol-4990/3/execution/node/243/log/
• https://staging.ci.brave.com/job/brave-browser-build-pr/job/francois-missing-copyright-symbol-4990/3/execution/node/402/log/

[bbondy]

Actually sorry this won't work because this file is auto-generated and copied from Chromium on each rebase. I think we'd have to do a dynamic modification instead, possibly inside brave-browser's lib/l10nUtil.js or script/chromium-rebase-l10n.py

[fmarier]

Moved to brave/brave-browser#6655.