Remove Dtrace/ZFS tests if their knobs are disabled

Prior to this change, Dtrace and ZFS tests and their respective
directories would remain installed even if `${MK_DTRACE_TESTS}` == no or
`${MK_ZFS_TESTS}` == no.

This change enhances the logic to remove the tests when the respective
knobs are disabled so the tests will be removed when `make delete-old`
is run.

MFC after:	2 weeks

tools/build/mk/OptionalObsoleteFiles.inc

@@ -1672,6 +1672,18 @@ OLD_DIRS+=usr/share/dtrace/toolkit
 OLD_DIRS+=usr/share/dtrace
 .endif
 
+.if ${MK_DTRACE_TESTS} == no
+DTRACE_TEST_DIRS=	cddl/usr.sbin/dtrace
+. for d in ${DTRACE_TEST_DIRS}
+.  if exists(${DESTDIR}${TESTSBASE}/${d}/)
+TESTS_DIRS!=find ${DESTDIR}${TESTSBASE}/${d}/ -type d | sed -e 's,^${DESTDIR}/,,'; echo
+OLD_DIRS+=${TESTS_DIRS}
+TESTS_FILES!=find ${DESTDIR}${TESTSBASE}/${d}/ -type f | sed -e 's,^${DESTDIR}/,,'; echo
+OLD_FILES+=${TESTS_FILES}
+.  endif
+. endfor
+.endif
+
 .if ${MK_EE} == no
 OLD_FILES+=usr/bin/edit
 OLD_FILES+=usr/bin/ee
@@ -9438,6 +9450,19 @@ OLD_DIRS+=usr/share/zfs/compatibility.d
 OLD_DIRS+=usr/share/zfs
 .endif
 
+.if ${MK_ZFS_TESTS} == no
+ZFS_TEST_DIRS=	cddl/usr.bin/ztest
+ZFS_TEST_DIRS+=	cddl/usr.sbin/zfsd
+. for d in ${ZFS_TEST_DIRS}
+.  if exists(${DESTDIR}${TESTSBASE}/${d}/)
+TESTS_DIRS!=find ${DESTDIR}${TESTSBASE}/${d}/ -type d | sed -e 's,^${DESTDIR}/,,'; echo
+OLD_DIRS+=${TESTS_DIRS}
+TESTS_FILES!=find ${DESTDIR}${TESTSBASE}/${d}/ -type f | sed -e 's,^${DESTDIR}/,,'; echo
+OLD_FILES+=${TESTS_FILES}
+.  endif
+. endfor
+.endif
+
 .if ${MK_ZONEINFO} == no
 OLD_FILES+=usr/share/zoneinfo/Africa/Abidjan
 OLD_FILES+=usr/share/zoneinfo/Africa/Accra