shadow: update to 4.2.1, add PKG_LICENSE

Signed-off-by: Steven Barth <steven@midlink.org>

utils/shadow/patches/001-busybox_ash.patch

@@ -1,9 +1,7 @@
-diff --git a/etc/login.defs b/etc/login.defs
-index 5b6fab3..79eeccf 100644
 --- a/etc/login.defs
 +++ b/etc/login.defs
 @@ -111,7 +111,7 @@ NOLOGINS_FILE	/etc/nologin
- # command is "-su".  If not defined, then "ps" would display the
+ # command as "-su".  If not defined, then ps(1) will display the
  # name of the shell actually being run, e.g. something like "-sh".
  #
 -SU_NAME		su