Refax/postfix: further fixes after last refax changes

[ethouris]

After comments from #2500

[codecov-commenter]

Codecov Report

Merging #2528 (2b78495) into master (e082f30) will increase coverage by 0.60%.
The diff coverage is 31.25%.

@@            Coverage Diff             @@
##           master    #2528      +/-   ##
==========================================
+ Coverage   64.81%   65.41%   +0.60%     
==========================================
  Files         100      100              
  Lines       19759    19767       +8     
==========================================
+ Hits        12807    12931     +124     
+ Misses       6952     6836     -116     

Impacted Files	Coverage Δ
srtcore/core.h	72.15% <ø> (ø)
srtcore/packet.cpp	44.04% <8.33%> (-1.91%)	⬇️
srtcore/core.cpp	60.33% <100.00%> (+1.20%)	⬆️
srtcore/queue.cpp	81.04% <0.00%> (-0.60%)	⬇️
test/test_bonding.cpp	94.21% <0.00%> (+0.52%)	⬆️
srtcore/api.cpp	54.59% <0.00%> (+1.31%)	⬆️
srtcore/buffer_snd.cpp	67.10% <0.00%> (+1.95%)	⬆️
srtcore/cache.h	83.07% <0.00%> (+3.07%)	⬆️
srtcore/window.h	100.00% <0.00%> (+3.27%)	⬆️
... and 2 more

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