how to use infer run a folder source code (include sub folder)?

Please make sure your issue is not addressed in the [FAQ](http://fbinfer.com/support.html#troubleshooting).

Please include the following information:
- [ ] The version of infer from `infer --version`.
- [ ] Your operating system and version, for example "Debian 9", "MacOS High Sierra", whether you are using Docker, etc.
- [ ] Which command you ran, for example `infer -- make`.
- [ ] The full output in a paste, for instance a [gist](https://gist.github.com/).
- [ ] If possible, a minimal example to reproduce your problem (for instance, some code where
infer reports incorrectly, together with the way you run infer to reproduce the incorrect
report).