libgcrypt: 1.6.3 -> 1.6.4

pkgs/development/libraries/libgcrypt/default.nix

···
 assert enableCapabilities -> stdenv.isLinux;
 
 stdenv.mkDerivation rec {
-  name = "libgcrypt-1.6.3";
+  name = "libgcrypt-1.6.4";
 
   src = fetchurl {
     url = "mirror://gnupg/libgcrypt/${name}.tar.bz2";
-    sha256 = "0pq2nwfqgggrsh8rk84659d80vfnlkbphwqjwahccd5fjdxr3d21";
+    sha256 = "09k06gs27gxfha07sa9rpf4xh6mvphj9sky7n09ymx75w9zjrg69";
   };
 
   buildInputs =