Use system ldns library

This library is used only by mod_enum and is available on most
platforms.  The version in our tree has many code quality problems
that are generating noise when doing static analysis.  Suffice it to
say we want rid of it as our responsibility.

FS-353

debian/control-modules

@@ -67,6 +67,7 @@ Description: Easyroute
 Module: applications/mod_enum
 Description: ENUM
  This module implements ENUM support.
+Build-Depends: libldns-dev
 
 Module: applications/mod_esf
 Description: Multicast support

debian/copyright

@@ -1264,36 +1264,6 @@ Files: libs/miniupnpc/bsdqueue.h
 Copyright: 1991,1993, The Regents of the University of California
 License: BSD-3-clause
 
-Files: libs/ldns/*
-Copyright: 2001-2010, NLnet Labs
- 2000-2001, Aaron D. Gifford
- 2000-2003 Damien Miller
- 1999 WIDE Project
- 1998 Todd C. Miller <Todd.Miller@courtesan.com>
- 1996, 1998 Internet Software Consortium.
- 1995 International Business Machines
-License: BSD-2-clause
-
-Files: libs/ldns/compat/fake-rfc2553.[ch]
- libs/ldns/examples/fake-rfc2553.h
- libs/ldns/ldns/rbtree.h
- libs/ldns/rbtree.c
- libs/win32/ldns/ldns-lib/util.h
-Copyright: 2001-2010, NLnet Labs
- 2000-2003 Damien Miller
- 1999 WIDE Project
-License: BSD-3-clause
-
-Files: libs/ldns/compat/b32_pton.c
- libs/ldns/compat/strlcpy.c
- libs/ldns/compat/b32_ntop.c
- libs/ldns/compat/b64_ntop.c
- libs/ldns/compat/inet_pton.c
-Copyright: 1996, 1998 Internet Software Consortium.
- 1995 International Business Machines, Inc.
- 1998 Todd C. Miller <Todd.Miller@courtesan.com>
-License: ISC
-
 Files: libs/js/*
 Copyright: 1998-2006 Mozilla <http://www.mozilla.org/>
  1996-2000 Netscape Communications Corporation

debian/license-reconcile.yml

@@ -1,13 +1,5 @@
 Rules:
  rules:
-  -
-   Glob: libs/ldns/*
-   Matches: NLnet\s*Labs,?\s*(20\d\d(|\s*-\s*20\d\d)|All\sright\sreserved)
-   Copyright: 2004-2010, NLnet Labs
-  -
-   Glob: libs/win32/ldns/ldns-lib/util.h
-   Matches: NLnet\s*Labs,?\s*(20\d\d(|\s*-\s*20\d\d)|All\sright\sreserved)
-   Copyright: 2004-2010, NLnet Labs
   -
    Glob: libs/miniupnpc/*
    Matches: Thomas\sBERNARD