Fix compile_filter on *BSD with non-ether linktypes

[gpotter2]

• fixes sr with filter not working on loopback on OpenBSD #4627

I really have no idea why this line exists in the first place. It makes very little sense to me

[gpotter2]

Ah I see, to allow to compile filters without root. I mean if the filters it compiles are broken it's not that useful.

Shouldn't be hard to fix if the interface type is provided from PFROUTE.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.55%. Comparing base (ef6da4b) to head (b194a7a).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4670      +/-   ##
==========================================
- Coverage   82.11%   81.55%   -0.57%     
==========================================
  Files         359      359              
  Lines       86576    86574       -2     
==========================================
- Hits        71096    70602     -494     
- Misses      15480    15972     +492     

Files with missing lines	Coverage Δ
scapy/arch/common.py	68.96% <100.00%> (-1.04%)	⬇️

... and 24 files with indirect coverage changes

[sthen]

Great, confirmed this fixes things for me. Many thanks!