pdns: use std::variant

[neheb]

Gets further away from boost.

I have:

• [x ] read the CONTRIBUTING.md document
• [x ] compiled this code

[coveralls]

Pull Request Test Coverage Report for Build 11086341914

Details

• 2 of 99 (2.02%) changed or added relevant lines in 4 files are covered.
• 5747 unchanged lines in 75 files lost coverage.
• Overall coverage decreased (-3.6%) to 61.085%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
pdns/lua-auth4.cc	0	4	0.0%
pdns/lua-base4.cc	2	19	10.53%
pdns/lua-record.cc	0	33	0.0%
modules/lua2backend/lua2api2.hh	0	43	0.0%

Files with Coverage Reduction	New Missed Lines	%
pdns/webserver.hh	1	69.16%
pdns/dnsdistdist/dnsdist-crypto.cc	1	76.01%
pdns/recursordist/ext/protozero/include/protozero/config.hpp	1	0.0%
pdns/recursordist/sortlist.hh	1	75.0%
pdns/iputils.hh	1	76.56%
pdns/dnstap.cc	2	68.82%
ext/probds/murmur3.cc	2	88.24%
pdns/dnsname.hh	2	91.36%
modules/gsqlite3backend/gsqlite3backend.cc	2	94.44%
pdns/recursordist/secpoll-recursor.cc	2	50.0%

Totals
Change from base Build 11066510928:	-3.6%
Covered Lines:	118987
Relevant Lines:	162138

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💛 - Coveralls

[rgacogne]

We will have to also teach LuaWrapper how to handle std::variant for this to fly, as for now it only handles boost::variant.

[neheb]

is that the reason for the failures?

[rgacogne]

is that the reason for the failures?

For at least some of them, yes:

Trying to cast a lua variable from "table" to "St6vectorISt4pairIiS_IS0_INSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEESt7variantIJbi7DNSNameS6_5QTypeEEESaISB_EEESaISE_EE"