Remove meta.license hack

pkgs/applications/networking/mailreaders/mailpile/default.nix

···
   meta = with stdenv.lib; {
     description = "A modern, fast web-mail client with user-friendly encryption and privacy features";
     homepage = https://www.mailpile.is/;
-    license = map (getAttr "shortName") [ licenses.asl20 licenses.agpl3 ];
+    license = [ licenses.asl20 licenses.agpl3 ];
     platforms = platforms.linux;
     maintainers = [ maintainers.iElectric ];
   };

pkgs/development/compilers/rustc/makeRustcDerivation.nix

···
       homepage = http://www.rust-lang.org/;
       description = "A safe, concurrent, practical language";
       maintainers = with maintainers; [ madjar cstrahan wizeman globin ];
-      license = map (builtins.getAttr "shortName") [ licenses.mit licenses.asl20 ];
+      license = [ licenses.mit licenses.asl20 ];
       platforms = platforms.linux;
     };