Changelog:
* Handle possible TOCTTOU issues in usermod/userdel (edneville)
* (CVE-2013-4235)
* Use O_NOFOLLOW when copying file
* Kill all user tasks in userdel
* Fix useradd -D segfault (Xi Ruoyao)
* Clean up obsolete libc feature-check ifdefs (Alejandro Colomar)
* Fix -fno-common build breaks due to duplicate Prog declarations
(Adam Sampson)
* Have single date_to_str definition (Alejandro Colomar)
* Fix libsubid SONAME version (Sam James)
* Clarify licensing info, use SPDX.