Remove unreferenced files

This commit removes files that are not referenced in nixpkgs anymore. I
have created this list by finding potential candidates using

  find nixpkgs/pkgs -type d -links 2 | parallel -N 1 'out=`grep -L {}  top-level/all-packages.nix`;  test -n "$out" && echo  {}'

and have then searched for those candidates with grep in whole nixpkgs.

pkgs/applications/misc/hello/ex-1/builder.sh

@@ -1,9 +0,0 @@
-source $stdenv/setup
-
-PATH=$perl/bin:$PATH
-
-tar xvfz $src
-cd hello-*
-./configure --prefix=$out
-make
-make install

pkgs/applications/misc/hello/ex-1/default.nix

@@ -1,16 +0,0 @@
-{stdenv, fetchurl, perl}:
-
-stdenv.mkDerivation {
-  name = "hello-2.1.1";
-  builder = ./builder.sh;
-  src = fetchurl {
-    url = mirror://gnu/hello/hello-2.1.1.tar.gz;
-    md5 = "70c9ccf9fac07f762c24f2df2290784d";
-  };
-  inherit perl;
-
-  meta = {
-    description = "GNU Hello, a classic computer science tool";
-    homepage = http://www.gnu.org/software/hello/;
-  };
-}