rec: coverity fixes, all minor optimizations

[omoerbeek]

Short description

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 12046188202

Details

• 3 of 3 (100.0%) changed or added relevant lines in 3 files are covered.
• 84 unchanged lines in 11 files lost coverage.
• Overall coverage decreased (-8.4%) to 64.693%

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Files with Coverage Reduction	New Missed Lines	%
pdns/dnsdistdist/dnsdist-crypto.cc	1	76.01%
pdns/recursordist/test-syncres_cc2.cc	3	88.91%
pdns/iputils.hh	3	78.29%
pdns/misc.cc	3	63.49%
pdns/iputils.cc	3	55.76%
pdns/rcpgenerator.cc	3	89.92%
pdns/recursordist/rec-tcp.cc	5	65.47%
pdns/dnsdistdist/dnsdist-tcp.cc	8	75.79%
pdns/recursordist/syncres.cc	10	79.64%
pdns/recursordist/taskqueue.cc	11	34.15%

Totals
Change from base Build 12034691735:	-8.4%
Covered Lines:	125855
Relevant Lines:	163658

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💛 - Coveralls