Revert "experimental/shadow"

This reverts commit 788e760b51.  NixOS
doesn't even have an /etc/skel.  And if we had, 1) NixOS has the
ability to create regular files rather than symlinks in /etc
(environment.etc.<file>.mode = ...), so files in /etc/skel that should
be copied as regular files can be supported; and 2) we may actually
*want* to copy a symlink.

Also, typos in file names.  Bleh.

pkgs/os-specific/linux/shadow/default.nix

@@ -24,19 +24,7 @@ stdenv.mkDerivation rec {
 
   buildInputs = stdenv.lib.optional (pam != null && stdenv.isLinux) pam;
 
-  patches = [ ./keep-path.patch dots_in_usernames 
-    /* nixos managed /etc[/skel] files are symlinks pointing to /etc/static[/skel]
-    * thus useradd will create symlinks ~/.bashrc. This patch fixes it: If a file
-    * should be copied to user's home directory and it points to /etc/static
-    * the target of the symbolic link is copied instead.
-    * This is only one way to fix it. The alternative would be making nixos
-    * create files in /etc/skel and keep some state around so that it knows
-    * which files it put there so that it can remove them itself. This more
-    * complicated approach would pay off if multiple apps woulb be using
-    * /etc/skel
-    */
-    ./etc-copy-etc-satic-target.patch
-    ];
+  patches = [ ./keep-path.patch dots_in_usernames ];
 
   # Assume System V `setpgrp (void)', which is the default on GNU variants
   # (`AC_FUNC_SETPGRP' is not cross-compilation capable.)

pkgs/os-specific/linux/shadow/etc-copy-etc-satic-target.patch

@@ -1,32 +0,0 @@
-diff --git a/libmisc/copydir.c b/libmisc/copydir.c
-index fac585c..ddf3788 100644
---- a/libmisc/copydir.c
-+++ b/libmisc/copydir.c
-@@ -490,6 +490,27 @@ static int copy_symlink (const char *src, const char *dst,
- 	if (NULL == oldlink) {
- 		return -1;
- 	}
-+      
-+        /* NixOS hack: if the link points to a file in /etc/static/ this
-+         * means the file is managed by nix and probably its meant to be a
-+         * file. So derefence once more until the original store path (real file)
-+         * is found*/
-+
-+
-+	if (strncmp (oldlink, "/etc/static/", strlen ("/etc/static/")) == 0) {
-+          char *target = readlink_malloc (oldlink);
-+          free (oldlink);
-+          int r = copy_entry(target, dst, reset_selinux, old_uid, new_uid, old_gid, new_gid);
-+
-+          /* make writeable by user */
-+          struct stat s;
-+          stat(dst, &s);
-+          s.st_mode |= S_IWUSR; // u+w
-+          chmod(dst, s.st_mode); // not minding higher bits because chmod (coreutils) doesn't either
-+
-+          free (target);
-+          return r;
-+        }
- 
- 	/* If src was a link to an entry of the src_orig directory itself,
- 	 * create a link to the corresponding entry in the dst_orig