Update the current RTP parser fuzzer to handle header extensions.

This changes the corpus semantics, but libfuzzer should be smart enough to figure it out, and if not then we can add a seed_corpus to help.

BUG=webrtc:4771
NOTRY=true

Review-Url: https://codereview.webrtc.org/2072473002
Cr-Original-Commit-Position: refs/heads/master@{#13384}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 36a321d2e32bd9d823329958a71d4eba8356522a
2 files changed