Add lmdb regression tests to meson

[fredmorcos]

Short description

Add lmdb regression tests to meson

Checklist

I have:

• read the CONTRIBUTING.md document
• compiled this code
• tested this code
• included documentation (including possible behaviour changes)
• documented the code
• added or modified regression test(s)
• added or modified unit test(s)
• checked that this code was merged to master

[coveralls]

Pull Request Test Coverage Report for Build 10688384915

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 4099 unchanged lines in 80 files lost coverage.
• Overall coverage decreased (-2.1%) to 62.519%

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Files with Coverage Reduction	New Missed Lines	%
pdns/base64.cc	1	80.6%
pdns/comment.hh	1	0.0%
pdns/recursordist/recursor_cache.cc	1	86.32%
pdns/query-local-address.cc	2	89.36%
pdns/recursordist/sortlist.cc	2	72.94%
pdns/recursordist/aggressive_nsec.cc	2	66.1%
pdns/dnswriter.cc	2	81.91%
ext/yahttp/yahttp/router.cpp	2	56.22%
ext/yahttp/yahttp/utility.hpp	2	36.53%
pdns/json.hh	2	0.0%

Totals
Change from base Build 10685140594:	-2.1%
Covered Lines:	104332
Relevant Lines:	136764

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💛 - Coveralls