debian/copyright: Update path to MD5 code

The lib/ directory was renamed to lib/dpkg/ in commit 01d0532
(Move libraries to subdirectories under lib/, 2009-07-15).
Update the copyright file accordingly.

debian/changelog

@@ -11,6 +11,8 @@ dpkg (1.15.5) UNRELEASED; urgency=low
   * Fix small leak when parsing ‘--ignore-depends’ option values.
   * When start-stop-daemon fails to set the io scheduling warn instead of
     finishing fatally.
+  * Update md5 file paths in debian/copyright.
+    Thanks to Jonathan Nieder <jrnieder@gmail.com>.
 
   [ Raphaël Hertzog ]
   * Add versioned dependency on base-files (>= 5.0.0) to dpkg-dev to ensure

debian/copyright

@@ -30,7 +30,7 @@ Copyright © 1994 Matt Welsh <mdw@sunsite.unc.edu>
 Copyright © 1994 Ian Murdock <imurdock@debian.org>
 
 Includes public domain MD5 code:
-	lib/md5.c and lib/md5.h originally written by Colin Plumb,
+	lib/dpkg/md5.c and lib/dpkg/md5.h originally written by Colin Plumb,
 
 Includes code from ‘getopt’ and ‘gettext’:
 	Copyright © 1984-2002 Free Software Foundation, Inc.