gnupg: 2.1.22 -> 2.1.23

This release in a RC for gnupg-2.2. The main difference as far as
nixpkgs is concerned is that the binary `gpg2` is now called `gpg` and
`gpgv2` is called `gpgv`.

This update fixed all explicit use of `gpg2` and `gpgv2` across nixpkgs,
but there might be some packaged software that internally use `gpg2`
not handeled by this commit.

See http://lists.gnu.org/archive/html/info-gnu/2017-08/msg00001.html
for full release information

pkgs/os-specific/linux/tomb/default.nix

@@ -28,8 +28,7 @@ stdenv.mkDerivation rec {
     install -Dm755 tomb       $out/bin/tomb
     install -Dm644 doc/tomb.1 $out/share/man/man1/tomb.1
 
-    # it works fine with gnupg v2, but it looks for an executable named gpg
-    ln -s ${gnupg}/bin/gpg2 $out/bin/gpg
+    ln -s ${gnupg}/bin/gpg $out/bin/gpg
 
     wrapProgram $out/bin/tomb \
       --prefix PATH : $out/bin:${lib.makeBinPath [ cryptsetup gettext pinentry ]}