Address some clang-tidy gripes.

Change-Id: I9cc48dc0619a6903c1b9f1f3a734e366c4e764a6
Reviewed-on: https://code-review.googlesource.com/c/re2/+/40010
Reviewed-by: Paul Wankadia <junyer@google.com>
(cherry picked from commit 374ecc8d98421ac3a77b0c76eab4a8a46e27e318)
Reviewed-on: https://code-review.googlesource.com/c/re2/+/40011
2 files changed