pfroute: parse routing messages on NetBSD correctly

[evverx]

pfroute: adjust the size of ifi_lastchange on NetBSD

NetBSD switched to 64-bit time_t in
https://www.netbsd.org/releases/formal-6/NetBSD-6.0.html so the size of
struct timespec is (8+4) bytes.

Closes: #5054

pfroute: round up sockaddrs on NetBSD correctly

NetBSD switched to uint64_t in
NetBSD/src@23cb540
to make the routing socket interface act identically for both 32 and 64
bit programs.

It's a draft because it needs tests and more testing in general but with this PR applied scapy no longer fails to start, conf.ifaces and conf.route look correct, conf.route.route no longer complains about the missing default route and so on.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.70%. Comparing base (5e13d41) to head (00a3ba4).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5073      +/-   ##
==========================================
- Coverage   80.50%   79.70%   -0.81%     
==========================================
  Files         390      372      -18     
  Lines       96785    96487     -298     
==========================================
- Hits        77920    76908    -1012     
- Misses      18865    19579     +714     

Files with missing lines	Coverage Δ
scapy/arch/bpf/pfroute.py	92.62% <100.00%> (-0.03%)	⬇️

... and 298 files with indirect coverage changes

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