Merge: jwrapper: prevent nitls to parse the generated files

Prevent nitls to parse the generated files by adding an empty `packages.ini` file to the examples folder. This slowed down calls to `make` as nitls is used to detect the dependancies of Nit programs and it took a while to parse the huge generated files.

Pull-Request: #1702
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Romain Chanoir <chanoir.romain@courrier.uqam.ca>
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>