[3.0] package: apple: backport build script for iOS
The build script allows building for iOS/tvOS without pulling the whole VLCKit project, to build a standalone library for integrating libvlc in applications.
The main goal is being able to maintain libVLC 3.0 without requiring the whole VLCKit environment to run tests.
Cherry-picked from master branch at commit version 44d44176 and modified the build.conf to have all enabled contribs building.
Edited by Felix Paul Kühne