nsd: Update to 4.3.5

Changelog:
19 January 2021: Wouter
- Set branch ready for 4.3.5 release.

15 January 2021: Wouter
- Fix #152: '*' in Rdata causes the return code to be NOERROR instead
  of NX.
- Add config.guess and config.sub to .gitignore for autoconf 2.70.
- Fix #150: TXT record validation difference with BIND.
- Fixup TXT record validation fix for escaped quotes.
- Fixup TXT record validation fix for escaped backslashes.
- Fixup escape character parse for quoted strings.

11 January 2021: Wouter
- Fix #151: DNAME not applied more than once to resolve the query.
- Fix dname test for #148.
- For #151: fix to not produce loops in output.

5 January 2021: Wouter
- Fix configure.ac for autoconf 2.70.

4 January 2021: Wouter
- Fix #148: CNAME need not be followed after a synthesized CNAME
  for a CNAME query.

11 December 2020: Wouter
- Fix that nsd-control has timeout when connection is down.
- remove windows socket ifdefs from nsd-control.

3 December 2020: Wouter
- For #145: Fix that service of remaining TCP and TLS connections
  does not allow new queries to be made, the connection is closed.
  Only existing queries and zone transfers are answered, new ones
  are rejected by a close of the channel.

30 November 2020: Wouter
- Fix #144: fix better.

27 November 2020: Wouter
- Fix #144: Typo fix in nsd.conf.5.in.

26 November 2020: Wouter
- Fix #143: xfrd no hysteresis with NOT IMPLEMENTED rcode.

(ryoon)