dns/dnstable: upgrade to version 1.2.0

dnstable 1.2.0:

• Implement indexing using RRtypes for ENTRY_TYPE_RRSET_NAME_FWD and ENTRY_TYPE_RDATA_NAME_REV entries. This uses RFC6840 RRtype bitmaps as the primary data structure.
• Added support for dnstable entries encoding version information and time metadata.
• The version entries, time metadata, and rrtype index information are generated by an updated dnstable-convert. Files generated by the old dnstable-convert will be processed as they were with the previous dnstable versions i.e., the new entry types and rrset index information will be absent.
• Add -R flag to dnstable_dump and dnstable_lookup to add raw rdata representation to outputs.
• Add long options to dnstable_dump to fix bug in not accepting some options properly.
• Fix dnstable_lookup usage output.
• Refactor time formatters and fix compiler warnings.
• Ignore entries which fail decoding for use with legacy empty data.
• Miscellaneous documentation improvements.

Sponsored by: Farsight Security, Inc.