Update to version 1.5.10

In this release there is a fix for long downtime after connectivity
loss, which was a longstanding unsolved issue. Features for tcp, TCP
Fast Open and timeout pressure to close connections when the tcp
connections are getting full. Option to use ipv6 /64 for extra entropy.

Features

• Create a pkg-config file for libunbound in contrib.
• TCP Fast open patch from Sara Dickinson.
• Finegrained localzone control with define-tag, access-control-tag, access-control-tag-action, access-control-tag-data, local-zone-tag, and local-zone-override. And added types always_transparent, always_refuse, always_nxdomain with that.
• If more than half of tcp connections are in use, a shorter timeout is used (200 msec, vs 2 minutes) to pressure tcp for new connects.
• [bugzilla: 787 ] Fix #787: outgoing-interface netblock/64 ipv6 option to use linux freebind to use 64bits of entropy for every query with random local part.
• For #787: prefer-ip6 option for unbound.conf prefers to send upstream queries to ipv6 servers.
• Add default root hints for IPv6 E.ROOT-SERVERS.NET, 2001:500:a8::e.
• keep debug symbols in windows build.

PR: 213043
Submitted by: maintainer