Let Scapy load on unsupported platforms

[gpotter2]

• let Scapy load on unsupported platforms
  • mock the required arch functions (read_routes, etc.)
  • fix a dependency loop on those platforms, by putting L3RawSocket6 next to its brother L3RawSocket

It's still miserable but at least it loads.

[codecov]

Codecov Report

Merging #4111 (b4e5e76) into master (f0843cc) will decrease coverage by 0.02%.
The diff coverage is 15.00%.

@@            Coverage Diff             @@
##           master    #4111      +/-   ##
==========================================
- Coverage   81.95%   81.93%   -0.02%     
==========================================
  Files         330      330              
  Lines       76145    76161      +16     
==========================================
+ Hits        62405    62406       +1     
- Misses      13740    13755      +15     

Files Changed	Coverage Δ
scapy/arch/__init__.py	73.43% <0.00%> (-16.95%)	⬇️
scapy/config.py	84.33% <0.00%> (+0.34%)	⬆️
scapy/interfaces.py	96.60% <0.00%> (ø)
scapy/supersocket.py	74.77% <50.00%> (-1.43%)	⬇️

... and 3 files with indirect coverage changes

[p-l-]

Thanks @gpotter2, that's a great idea! No reason one cannot dissect packets from a PCAP file on an unsupported platform!