Log Message:
nsd: Update to 4.2.4

Changelog:
3 December 2019: Wouter
	- Fix #52: do not log transient network full errors unless higher
	  verbosity is set.
	- Fix checkconf test for new error output string.
	- tag for 4.2.4rc1 release.

27 November 2017 Jeroen
	- Fix regressions in configparser.y

22 November 2019: Wouter
	- Fix #48: Add make distclean that removes config.h made by configure.
	  And add maintainer-clean that removes bison and flex output.

18 November 2019: Wouter
	- Detect fixed time memcmp for openssl 0.9.8 compatibility.
	- Detect EC_KEY_new_by_curve_name for openssl 0.9.8.
	- include limits.h for UINT_MAX.
	- If no recvmmsg, dont use msg_flags member, but errno for error,
	  where our fallback function left it, msg_flags also does not exist
	  on some systems.
	- Remove unused variable warning for portability.

14 November 2019: Wouter
	- Fix checkconf test with filenames that sort in the same order.
	- Tag for 4.2.3rc1.  Branch master is 4.2.4 in development.

11 November 2019: Wouter
	- Fix #44: document that remote-control is a top-level nsd.conf
	  attribute.
	- Fix compile on OSX.
	- Fix for #44: nicer top-level clause documentation.

22 October 2019: Jeroen
	- Number of different UDP handlers has been reduced to one. recvmmsg
	  and sendmmsg implementations are now used on all platforms.
	  Compatible implementations are in place for systems that lack the
	  system calls.
	- Socket options are now set in designated functions for easy reuse.
	- Socket setup has been simplified for easy reuse.
	- Configuration parser is now aware of the context in which an option
	  was specified.

21 October 2019: Wouter
	- For #21 add
	  contrib/patch_for_s6_startup_and_other_service_supervisors.diff
	  that adds support for readiness notification with READY_FD from
	  Cameron Nemo.

17 October 2019: Jeroen
	- Fix #40: Merge small fixes for confine-to-zone by Greg Bock.

15 October 2019: Jeroen
	- For #39: Merge confine-to-zone feature contributes by Greg Bock.

26 September 2019: Wouter
	- Fix #38: log address and failure reason with tls handshake errors,
	  squelches (the same as unbound) some unless high verbosity is used.
	- Fixup clang analysis warning in xfrd_parse_received_xfr_packet
	  master dereference.

25 September 2019: Wouter
	- The nsd.conf includes are sorted ascending, for include statements
	  with a '*' from glob.

16 September 2019: Wouter
	- Fixup warnings during --disable-ipv6 compile.
	- Fixup unit test executable to run without IPv6.

4 September 2019: Wouter
	- Fix #35: excessive logging of ixfr failures, it stops the log when
	  fallback to axfr is possible. log is enabled at high verbosity.

2 September 2019: Wouter
	- For #21: pidfile "" allows to run NSD without a pidfile, for
	  startup management tools like daemontools.

28 August 2019: Wouter
	- In tests check for tls test tool availability.