New review comment by classabbyamp on void-packages repository

https://github.com/void-linux/void-packages/pull/38344#discussion_r932584327

Comment:
> Asterisk is distributed under the GNU General Public License version 2
> and is also available under alternative licenses negotiated directly
> with Digium, Inc. If you obtained Asterisk under the GPL, then the GPL
> applies to all loadable Asterisk modules used on your system as well,
> except as defined below. The GPL (version 2) is included in this
> source tree in the file COPYING.
> 
> This package also includes various components that are not part of
> Asterisk itself; these components are in the 'contrib' directory
> and its subdirectories. These components are also distributed under the
> GPL version 2 as well.

What part of it is proprietary? (also, if there are proprietary bits, it should probably also have `repo=nonfree`)