build(deps): bump third_party/gflags from 03a4842 to 58cf1ef

Bumps [third_party/gflags](https://github.com/gflags/gflags) from `03a4842` to `58cf1ef`.
- [Release notes](https://github.com/gflags/gflags/releases)
- [Commits](gflags/gflags@03a4842...58cf1ef)

---
updated-dependencies:
- dependency-name: third_party/gflags
  dependency-type: direct:production
...

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