Merge from stable/11 bspatch, portsnap, and libarchive fixes:

bspatch

MFS r306213: bspatch Capsicumization, sanity checks, and other improvements

r304691: bspatch: apply style(9)

Make style changes (and trivial refactoring of open calls) now in order
to reduce noise in diffs for future capsicum changes.

r304807 (allanjude): Capsicumize bspatch

Move all of the fopen() and open() calls to the top of main()

Restrict each FD to least privilege (read/seek only, write only, etc)

cap_enter(), and make all except the output FD read/seek only.

r304821: bspatch: remove output file in the case of error

r305486: bspatch: add sanity checks on sizes to avoid integer overflow

Note that this introduces an explicit 2GB limit, but this was already
implicit in variable and function argument types.

This is based on the "non-cryptanalytic attacks against freebsd
update components" anonymous gist. Further refinement is planned.

r305737: bspatch: remove superfluous newlines from errx strings

r305822: bspatch: use #define for header size instead of magic number

r306026: bspatch: Remove backwards-compatibility sys/capability.h support

bspatch previously included sys/capability.h or sys/capsicum.h based
on __FreeBSD_version, as FreeBSD is the upstream for bsdiff and we may
see this file incorporated into other third-party software.

The Capsicum header is now installed as sys/capsicum.h in stable/10 and
FreeBSD 10.3, so we can just use sys/capsicum.h and simplify the logic.

With this change, bspatch is identical between head, stable/11 and releng/11.0.

portsnap

MFS r305648 (delphij): MFC r305469:

Ensure that we always open only files that is named by explicitly
using shell redirections instead of having gzip(1) to decide what
file to open.

Issue reported in the "non-cryptanalytic attacks against freebsd
update components" anonymous gist.

libarchive

MFS r305754 (mm): MFC r305422:

Sync libarchive with vendor

Vendor issues fixed:
PR #777: Multiple bugfixes for setup_acls()

This includes a bugfix for a bug that caused ACLs not to be read properly
for files and directories inside subdirectories and as a result not being
stored or being incorrectly stored in tar archives.

MFS r306321 (mm): MFC r305819:

Sync libarchive with vendor including important security fixes.

Issues fixed (FreeBSD):
PR #778: ACL error handling
Issue #745: Symlink check prefix optimization is too aggressive
Issue #746: Hard links with data can evade sandboxing restrictions

This update fixes the vulnerability #3 and vulnerability #4 as reported in
"non-cryptanalytic attacks against FreeBSD update components".
https://gist.github.com/anonymous/e48209b03f1dd9625a992717e7b89c4f

Fix for vulnerability #2 has already been merged.

Approved by: re (gjb), so (glebius)