dnsdist: Gracefully fall back to older versions of Quiche

[rgacogne]

Short description

Before this commit we only tried older versions of Quiche if the quiche feature was not explicitely enabled, and failed otherwise.

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)

[coveralls]

Pull Request Test Coverage Report for Build 13202443191

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 67 unchanged lines in 12 files lost coverage.
• Overall coverage increased (+0.4%) to 64.723%

---

Files with Coverage Reduction	New Missed Lines	%
modules/gpgsqlbackend/gpgsqlbackend.cc	1	88.62%
modules/remotebackend/remotebackend.cc	1	35.37%
pdns/recursordist/aggressive_nsec.cc	2	66.1%
pdns/recursordist/syncres.cc	3	80.19%
pdns/remote_logger.cc	3	53.81%
modules/gpgsqlbackend/spgsql.cc	3	68.42%
pdns/dnsdistdist/dnsdist.cc	4	68.73%
pdns/signingpipe.cc	5	85.52%
pdns/recursordist/test-syncres_cc1.cc	6	89.95%
pdns/recursordist/rec-tcpout.cc	8	50.79%

Totals
Change from base Build 13202316570:	0.4%
Covered Lines:	128274
Relevant Lines:	167097

---

💛 - Coveralls

[miodvallat]

I'm not meson-literate enough to be sure I understand this completely, but it does not raise any alarm when looking at it.