MFC r342153, r342172-r342173

r342153:
Conditionally install /etc/rc.d/audit* based on ${MK_AUDIT}

/usr/sbin/audit(dist)?d are only installed if ${MK_AUDIT} == yes. Their
supporting scripts should only be installed in those instances as well.

Submitted by: ngie
Reviewed by: emaste
Pull Request: https://github.com/freebsd/freebsd/pull/242

r342172:
audit(4) tests: require /etc/rc.d/auditd

These tests should be skipped if /etc/rc.d/auditd is missing, which could be
the case if world was built with WITHOUT_AUDIT set. Also, one test case
requires /etc/rc.d/accounting.

Submitted by: ngie
Pull Request: https://github.com/freebsd/freebsd/pull/240

r342173:
Conditionalize installtion audit(4) tests on MK_AUDIT

MK_AUDIT already controls auditd(8), praudit(1), etc. It should also control
the audit test suite.

Submitted by: ngie
Pull Request: https://github.com/freebsd/freebsd/pull/240