tests-extra: don't compare RFC5155/B.5 test with BIND9

Explained in the test, BIND9 as of 9.9.4 provides wrong closest
encloser wildcard NSEC3 record.

tests-extra/tests/basic/opt-out/test.py

@@ -44,7 +44,10 @@ resp.cmp(bind)
 # B5. Wildcard No Data Error.
 resp = knot.dig("a.z.w.example.", "AAAA", dnssec=True)
 resp.check(rcode="NOERROR", flags="QR AA", eflags="DO")
-resp.cmp(bind)
+# @note Commented out because BIND9 (as of 9.9.4) does not return
+#       a closest encloser wildcard NSEC3 RR.
+#       See RFC5155 appendix B.5, page 46
+#resp.cmp(bind)
 
 # B6. DS Child Zone No Data Error.
 resp = knot.dig("example.", "DS", dnssec=True)