Bound pcap record lengths before reading

[guedou]

Here is a fix for: https://issues.oss-fuzz.com/issues/559831856

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.35%. Comparing base (251daec) to head (129f90a).
⚠️ Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5178      +/-   ##
==========================================
- Coverage   81.13%   80.35%   -0.79%     
==========================================
  Files         392      374      -18     
  Lines       97843    97578     -265     
==========================================
- Hits        79384    78404     -980     
- Misses      18459    19174     +715     

Files with missing lines	Coverage Δ
scapy/utils.py	73.59% <100.00%> (+0.30%)	⬆️

... and 300 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.