Address clang-tidy suggestions in src/pathops

Change-Id: I3c1b9cfcab387d458d87ab2b6d10b48b6556f743
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/817218
Reviewed-by: Nicolette Prevost <nicolettep@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
2 files changed