Compile script: add a reset option

Description

Sometimes, when we apply patches or some changes are made, the current state of the medialibrary or VLC checked out repos prevent the compilation to be done.

We should add a --reset (or whatever we want call it) option to the script to completely remove the ./vlc and ./medialibrary/medialibrary folders.

It should ask for a confirmation, telling the user that any change on the repos will be lost.