dns/dnsdbq: upgrade to version 2.5.5

• clarify dnsdb is dnsdb2 and when to use dnsdb1 (#177)
• clarify relationship of -c to -A/-B, in both main text and examples (#181)
• dedup the PDNS JSON presentation (lookup vs. summarize) (#180)
• add -0 option to test countoff()
• shelter callers of countoff() from its recursive innards; change counted->nlabel
• change counted->nlabel from size_t to int
• if there are no alnums, cons up a "." string, in sortable_dnsname()
• gcc-11 caught an if statement that needed curly brackets
• cleanups

Sponsored by: Farsight Security, Inc.