Fix port->set() dtls compile error

[Yurunsoft]

No description provided.

[codecov]

Codecov Report

Merging #3947 (2be2541) into master (e741fbd) will increase coverage by 0.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #3947      +/-   ##
==========================================
+ Coverage   48.99%   49.00%   +0.01%     
==========================================
  Files          69       69              
  Lines       12967    12967              
==========================================
+ Hits         6353     6355       +2     
+ Misses       6614     6612       -2     

Impacted Files	Coverage Δ
src/server/port.cc	53.74% <0.00%> (-0.33%)	⬇️
src/os/async_thread.cc	70.81% <0.00%> (ø)
src/protocol/base.cc	66.66% <0.00%> (+2.04%)	⬆️

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