MFC many audit(4) tests.

MFC r334471, r334487, r334496, r334592, r334668, r334933, r335067, r335105,
r335136, r335140, r335145, r335207-r335208, r335215, and r335255-r335256.

r334471:
audit(4): Add tests for the fr class of syscalls

readlink and readlinkat are the only syscalls in this class. open and
openat are as well, but they'll be handled in a different file. Also, tidy
up the copyright headers of recently added files in this area.

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15636

r334487:
audit(4): Add tests for the fw class of syscalls.

truncate and ftruncate are the only syscalls in this class, apart from
certain variations of open and openat, which will be handled in a different
file.

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15640

r334496:
audit(4): add tests for the fd audit class

The only syscalls in this class are rmdir, unlink, unlinkat, rename, and
renameat. Also, set is_exclusive for all audit(4) tests, because they can
start and stop auditd.

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15647

r334592:
audit(4): add tests for the cl audit class

The only syscalls in this class are close, closefrom, munmap, and revoke.

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15650

r334668:
audit(4): add tests for open(2) and openat(2)

These syscalls are atypical, because each one corresponds to several
different audit events, and they each pass several different audit class
filters.

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15657

r334933:
audit(4): add tests for stat(2) and friends

This revision adds auditability tests for stat, lstat, fstat, and fstatat,
all from the fa audit class. More tests from that audit class will follow.

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15709

r335067:
audit(4): Fix file descriptor leaks in ATF tests

Submitted by: aniketp
Reported by: Coverity
CID: 1393343 1393346 1392695 1392781 1391709 1392078 1392413
CID: 1392014 1392521 1393344 1393345 1393347 1393348 1393349
CID: 1393354 1393355 1393356 1393357 1393358 1393360 1393362
CID: 1393368 1393369 1393370 1393371 1393372 1393373 1393376
CID: 1393380 1393384 1393387 1393388 1393389
Sponsored by: Google, Inc (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15782

r335105:
audit(4): add tests for statfs(2), fstatfs(2), and getfsstat(2)

Submitted by: aniketp
Sponsored by: Google, Inc (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15750

r335136:
audit(4): add tests for flock, fcntl, and fsync

Submitted by: aniketp
Sponsored by: Google, Inc (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15795

r335140:
audit(4): fix typo from r335136

Typo in Makefile accidentally disabled some older tests

X-MFC-With: 335136

r335145:
audit(4): add tests for fhopen, fhstat, and fhstatfs

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15798

r335207:
audit(4): add tests for access(2), chmod(2), and friends

access(2), eaccess(2), faccessat(2), chmod(2), fchmod(2), lchmod(2), and
fchmodat(2).

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15805
Differential Revision: https://reviews.freebsd.org/D15808

r335208:
audit(4): improve formatting in tests/sys/audit/open.c

[skip ci]

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15797

r335215:
audit(4): Add a few tests for network-related syscalls

Add tests for socket(2), socketpair(2), and setsockopt(2)

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15803

r335255:
audit(4): add tests for bind(2), bindat(2), and listen(2)

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15843

r335256:
audit(4): add tests for chown(2) and friends

Includes chown, fchown, lchown, and fchownat

Submitted by: aniketp
Sponsored by: Google, Inc. (GSoC 2018)
Differential Revision: https://reviews.freebsd.org/D15825