apps/AboutSystem NetBSD licences and xfree86 url

* Adds licence information for the NetBSD contributions
* ftp - 4 clause BSD (retained in ftp.c)
* tput - Berkeley
(http://cvsweb.netbsd.org/bsdweb.cgi/src/usr.bin/tput/tput.c?rev=1.26)

* Berkeley licence text added to licences

* xfree86.org url added

These were previously marked TODOs

Change-Id: I01bf0bb6055b3b45ca80c6cddabdb093cb043408
Reviewed-on: https://review.haiku-os.org/c/887
Reviewed-by: Stephan Aßmus <superstippi@gmx.de>