Remove unneeded cpio dependency from dpkg-dev

dpkg-source used to call cpio to handle tar archives, but not anymore
for a long time.

debian/changelog

@@ -55,6 +55,7 @@ dpkg (1.15.0) UNRELEASED; urgency=low
   * Add initial C unit test suite for libdpkg.
   * Sanitize --status-fd output by replacing newlines with spaces.
     Closes: #505172
+  * Remove unneeded cpio dependency from dpkg-dev.
 
   [ Raphael Hertzog ]
   * Enhance dpkg-shlibdeps's error message when a library can't be found to

debian/control

@@ -33,7 +33,7 @@ Package: dpkg-dev
 Section: utils
 Priority: optional
 Architecture: all
-Depends: dpkg (>= 1.14.6), perl5, perl-modules, cpio (>= 2.4.2-2), bzip2, lzma,
+Depends: dpkg (>= 1.14.6), perl5, perl-modules, bzip2, lzma,
  patch (>= 2.2-1), make, binutils, libtimedate-perl
 Recommends: gcc | c-compiler, build-essential
 Suggests: gnupg, debian-keyring