Store if source code file paths contain "third party" hints

When processing source code packages it would be useful to store if the path names contain some hints that indicate that a file is actually coming from another package and has been copied into the package being processed. To give some examples: there are packages (Chromium, LibreOffice, Qt, etc.) that provide their own copies of dependencies instead of using the system provided dependencies. They are often in directories that hint at an external origin, such as:

- 3rdparty
- 3rd-party-lib
- 3rdpart
- contrib
- external
- thirdparty
- third_party
- third-party
- third-party-tools

and possibly more.