auth: Fix a bunch of issues when building with meson

[rgacogne]

Short description

This PR contains patches submitted by @RvdE in #13987 and one from @zeha submitted in #16702.
It fixes the issues reported in #13987 in my tests, but I couldn't reproduce the Unable to load module './libgpgsqlbackend.so': ./libgpgsqlbackend.so: Undefined symbol "_ZTV11GSQLBackend" so it's probably not fixed.
I did not pick up the GSQL related changed from #16702 because 1/ I couldn't check the fix because I cannot reproduce the issue 2/ they clearly do not work when more than one GSQL-based module is linked statically into the pdns_server binary, as reported by our CI.

Checklist

I have:

• read the CONTRIBUTING.md document
• read and accepted the Developer Certificate of Origin document, including the AI Policy, and added a "Signed-off-by" to my commits
• 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)

[miodvallat]

Well can't you use the endswith trick above here too?

[rgacogne]

I tried but I couldn't find how to apply a different treatment to the generated files, since a single command generates several of them. I attempted to not install from custom_target but to iterate over the generated files, calling install_man for every one of them with the correct directory, but that does not work if the files are not present in the build directory yet (which defeats the point).

[RvdE]

#13987 (comment)

The ternary operator does the trick to install the ixfrdist.yml.5 in the correct location

[rgacogne]

You are looking at the wrong location in the file, your fix (applied in this PR) works for the case where the man pages are present in the source directory (release tarball) but this case is when they aren't.

[coveralls]

Pull Request Test Coverage Report for Build 21073006167

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 62 unchanged lines in 12 files lost coverage.
• Overall coverage increased (+1.9%) to 73.358%

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Files with Coverage Reduction	New Missed Lines	%
pdns/pollmplexer.cc	1	84.97%
pdns/misc.cc	2	62.29%
pdns/query-local-address.cc	2	90.43%
pdns/recursordist/aggressive_nsec.cc	2	66.47%
pdns/dnsdistdist/dnsdist-carbon.cc	3	64.12%
pdns/rcpgenerator.cc	3	90.79%
pdns/recursordist/test-syncres_cc2.cc	3	89.18%
pdns/recursordist/syncres.cc	5	81.1%
pdns/recursordist/test-syncres_cc1.cc	8	90.19%
pdns/dnsdistdist/dnsdist-tcp.cc	9	77.27%

Totals
Change from base Build 21071469475:	1.9%
Covered Lines:	129096
Relevant Lines:	165175

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💛 - Coveralls