dns/dnsmasq-devel: update to 2.86test6

CHANGELOG additions since test5:

• Allow smaller then 64 prefix lengths in synth-domain, with caveats. --synth-domain=1234:4567::/56,example.com is now valid.

• Make domains generated by --synth-domain appear in replies when in authoritative mode.

Git log since v2.86test5:

• 8389b94 2021-07-21 | Better fix than f2266d9678d71633d62d70238be3782ea74019c9 (tag: v2.86test6) [Simon Kelley]
• f2266d9 2021-07-21 | Add UINT32_MAX if not defined by system. [Simon Kelley]
• 56bd806 2021-07-21 | Typo in new EDE code. [Simon Kelley]
• ac7eeea 2021-07-21 | Handle empty hostmaster in --auth-soa [Simon Kelley]
• b741059 2021-07-20 | Detect malformed --dhcp-relay option. [Simon Kelley]
• cbd9842 2021-07-20 | Fix argument checking for --dhcp-match. [Simon Kelley]
• 32e15c3 2021-07-20 | canonicalise_opt must always return heap memory. [Simon Kelley]
• f0dc324 2021-07-20 | Checks on prefix-length in --domain --synth-domain and --rev-server. [Simon Kelley]
• f83c6cf 2021-07-20 | Return REFUSED in auth mode when we are not authoritative for the query. [Simon Kelley]
• c068b3a 2021-07-19 | --synth-domain now works in auth mode. [Simon Kelley]
• adf9dec 2021-07-18 | Allow shorter IPv6 prefix lengths in (some) --synth-domain options. [Simon Kelley]
• 767d9cb 2021-07-09 | Add --quiet-tftp. [Kevin Darbyshire-Bryant]