Remove unreferenced licenses: BSD-1-clause, GPL-2

(Thanks, lintian)

debian/copyright

@@ -274,31 +274,6 @@ License: CC-BY
 Comment:
  Relevant discussion in https://github.com/rust-lang/rust/issues/11562
 
-License: BSD-1-clause
- Redistribution and use in source and binary forms, with
- or without modification, are permitted provided that the
- following conditions are met:
- .
- 1. Redistributions of source code must retain the
-    above copyright notice, this list of conditions
-    and the following disclaimer.
- .
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
- WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
- WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
- PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY
- DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
- USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
- USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- OF SUCH DAMAGE.
-
 License: BSD-2-clause
  Redistribution and use in source and binary forms, with
  or without modification, are permitted provided that the
@@ -560,10 +535,6 @@ License: SIL-OPEN-FONT
  DAMAGES, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  FROM, OUT OF THE USE OR INABILITY
 
-License: GPL-2
-  On Debian GNU/Linux systems, the complete text of the GNU General
-  Public License can be found in `/usr/share/common-licenses/GPL-2'.
-
 License: GPL-2+
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by