MFC note: tests/sys/kern/coredump_phnum_test.sh changes omitted

MFC r322214:

Make test scripts under tests/... non-executable

Executable bits should be set at install time instead of in the repo.
Setting executable bits on files triggers false positives with Phabricator.

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

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

Integrate tools/regression/mac/mac_bsdextended and
tools/regression/mac/mac_portacl into the FreeBSD test suite as
tests/sys/mac/bsdextended and tests/sys/mac/portacl, respectively

MFC after: 1 month
Sponsored by: EMC / Isilon Storage Division

Make the mac_portacl testcases work / more robust

- A trap(1) call has been added to the test scripts to better
ensure that the tests do a better job at trying to restore the
test host state at the end of the tests (if the test was
interrupted before it would leave the system in an odd state,
potentially making the test results for subsequent runs
non-deterministic).
- Add root user checks
- Fix nc(1) usage:
-- -o is deprecated
-- Using `-w 10` will make the call timeout after 10 seconds so it
doesn't block indefinitely
- Use local variables
- Be more terse in the error messages
- Parameterize out "127.0.0.1"

MFC after: 1 week
Sponsored by: EMC / Isilon Storage Division

Regression tests for mac_portacl(4).