licenses: Remove 'bsd-style'.

This procedure had been deprecated since March 2015.

* guix/licenses.scm (bsd-style): Remove.

guix/licenses.scm

 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2012, 2014, 2015, 2017 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2012, 2014, 2015, 2017, 2019 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2013, 2015 Andreas Enge <andreas@enge.fr>
 ;;; Copyright © 2012, 2013 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2015 Mark H Weaver <mhw@netris.org>
@@ -38,7 +38,6 @@ (define-module (guix licenses)
             boost1.0
             bsd-2 bsd-3 bsd-4
             non-copyleft
-            bsd-style                             ;deprecated!
             cc0
             cc-by2.0 cc-by3.0 cc-by4.0
             cc-by-sa2.0 cc-by-sa3.0 cc-by-sa4.0
@@ -170,12 +169,6 @@ (define* (non-copyleft uri #:optional (comment ""))
             "Check the URI for details.  "
             comment)))
 
-(define bsd-style
-  ;; This alias is kept for backward-compatibility.  Do not use it for new
-  ;; packages: it is ambiguous, as rightfully explained at
-  ;; <http://www.gnu.org/philosophy/words-to-avoid.html#BSD-style>.
-  non-copyleft)
-
 (define cc0
   (license "CC0"
            "http://directory.fsf.org/wiki/License:CC0"