release-small.nix: drop the Emacs 23.x packages from this file

Most of these packages are very old and don't compile in 'master' to
begin with, so it's probably not necessary to use them for testing the
stdenv-updates branch.

pkgs/top-level/release-small.nix

@@ -203,11 +203,4 @@ with (import ./release-lib.nix);
     tools = linux;
   };
 
-  emacs23Packages = {
-    bbdb = linux;
-    cedet = linux;
-    ecb = linux;
-    emacsw3m = linux;
-    emms = linux;
-  };
 } ))