Update dpkg-dev dependencies

- Move gnupg to Recommends. It's needed to sign .dsc and .changes.
- Add gpgv to Recommends. Useful to check signatures of extracted packages.
- Add debian-maintainers to Suggests. Together with debian-keyring they
  contain all the GPG keys required to verify official Debian packages.

debian/changelog

@@ -26,6 +26,11 @@ dpkg (1.15.1) UNRELEASED; urgency=low
     Closes: #489238
   * dpkg-source's signature check is now done with gpgv if possible and
     timeouts if not completed within 10 seconds. Closes: #490929
+  * Update dpkg-dev dependencies: Closes: #472942
+    - Move gnupg to Recommends. It's needed to sign .dsc and .changes.
+    - Add gpgv to Recommends. Useful to check signatures of extracted packages.
+    - Add debian-maintainers to Suggests. Together with debian-keyring they
+    contain all the GPG keys required to verify official Debian packages.
 
   [ Guillem Jover ]
   * Fix typo in dpkg output (‘unexecpted’ → ‘unexpected’). Closes: #519082

debian/control

@@ -35,8 +35,8 @@ Priority: optional
 Architecture: all
 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
+Recommends: gcc | c-compiler, build-essential, gnupg, gpgv
+Suggests: debian-keyring, debian-maintainers
 Conflicts: dpkg-cross (<< 2.0.0), devscripts (<< 2.10.26)
 Replaces: manpages-pl (<= 20051117-1)
 Description: Debian package development tools