Improve libsrtp fuzzer.

- Also check AES-256-GCM which is used by WebRTC.
- Also check AES-128 with 32 bit auth tag which is used by WebRTC.
- Update AES-128-GCM to use 16 octets tag as used by WebRTC.
- Enable encrypted header extensions depending on fuzzing input. This
  tests new functionality of WebRTC.

BUG=webrtc:3411

Change-Id: I076c4ae5be71dd09bfec4928e6b5b12be8fc428c
Reviewed-on: https://chromium-review.googlesource.com/612076
Commit-Queue: Joachim Bauch <jbauch@webrtc.org>
Reviewed-by: Max Moroz <mmoroz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#494182}
1 file changed