browserpass: Fix evaluation

When I backported https://github.com/NixOS/nixpkgs/pull/58639 to 18.09,
I didn't realize that buildGoPackage still required the `name`
attribute. Thanks to @primeos for notifying me of this.

pkgs/tools/security/browserpass/default.nix

@@ -7,6 +7,7 @@ let
   # folder
   v2 = callPackage ./2.nix {};
 in buildGoPackage rec {
+  name = "${pname}-${version}";
   pname = "browserpass";
   version = "3.0.1";