hrpsys: 315.2.1-2 in 'hydro/distribution.yaml' [bloom]

Increasing version of package(s) in repository `hrpsys` to `315.2.1-2`:

- distro file: `hydro/distribution.yaml`
- bloom version: `0.5.4`
- previous version for package: `315.2.1-1`

## hrpsys

```
* Merge pull request #83 <https://github.com/start-jsk/hrpsys/issues/83> from k-okada/add_git
  add build_depend to git
* Contributors: Kei Okada
```