[sanitizer] Add Scudo to the sanitizer lint checks.

Summary:
Scudo abides by the coding style enforced by the sanitizer_common
linter, but as of right now, it's not linter-enforced.

Add Scudo to the list of directories checked by check_lint.sh.

Also: fixes some linter errors found after getting this running.

Reviewers: cryptoad

Reviewed By: cryptoad

Subscribers: llvm-commits, kubamracek

Differential Revision: https://reviews.llvm.org/D39757

llvm-svn: 317699