Bump external/benchmark from b884717 to c19cfee

Bumps [external/benchmark](https://github.com/google/benchmark) from `b884717` to `c19cfee`.
- [Release notes](https://github.com/google/benchmark/releases)
- [Commits](google/benchmark@b884717...c19cfee)

---
updated-dependencies:
- dependency-name: external/benchmark
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>