Multiple fixes.

- unlock also passwords locked with passwd -l
- prevent breaking user entry by entering a password containing colon
- fix possible DoS when locking the database files for update
- properly use login.defs from the chroot in useradd

shadow-4.2.1-no-lock-dos.patch

@@ -0,0 +1,15 @@
+diff -up shadow-4.2.1/lib/commonio.c.no-lock-dos shadow-4.2.1/lib/commonio.c
+--- shadow-4.2.1/lib/commonio.c.no-lock-dos	2015-08-27 15:09:17.101537812 +0200
++++ shadow-4.2.1/lib/commonio.c	2015-08-27 15:11:06.643011248 +0200
+@@ -140,7 +140,10 @@ static int do_lock_file (const char *fil
+ 	int retval;
+ 	char buf[32];
+ 
+-	fd = open (file, O_CREAT | O_EXCL | O_WRONLY, 0600);
++	/* We depend here on the fact, that the file name is pid-specific.
++	 * So no O_EXCL here and no DoS.
++	 */
++	fd = open (file, O_CREAT | O_TRUNC | O_WRONLY, 0600);
+ 	if (-1 == fd) {
+ 		if (log) {
+ 			(void) fprintf (stderr,