Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Update ipfilter 4.1.28 --> 5.1.2.

Approved by: glebius (mentor)
BSD Licensed by: Darren Reed <darrenr@reed.wattle.id.au> (author)

- Prevent buffer overflow in IPFilter's load_http function used to load
ipfilter tables via http by the user-level ippool utility. Previously
the 1024-byte buffer used to store a http request coudld easily overflow
if the length of the hostname part of the url passes exceeded 496 bytes. [1]
- Use snprintf to prevent possieble buffer overflows in future. [2]
- Do not try to close the descriptor twice on failure. [2]

Reported by: Maksymilian Arciemowicz <cxib@securityreason.com> [1]
Obtained from: NetBSD CVS [2]
MFC after: 2 weeks

This commit was generated by cvs2svn to compensate for changes in r170263,
which included commits to RCS files with non-trunk default branches.

Import IPFilter 4.1.23 to vendor branch.
See src/contrib/ipfilter/HISTORY for details of changes since 4.1.13