gencpp: 0.5.2-0 in 'indigo/distribution.yaml' [bloom]

Increasing version of package(s) in repository `gencpp` to `0.5.2-0`:

- distro file: `indigo/distribution.yaml`
- bloom version: `0.5.5`
- previous version for package: `0.5.1-0`

## gencpp

```
* add architecture_independent flag in package.xml (#19 <https://github.com/ros/gencpp/issues/19>)
```