Don't set V bit in flexible mode

BUG=webrtc:4914

Review URL: https://codereview.webrtc.org/1291163007

Cr-Original-Commit-Position: refs/heads/master@{#9848}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 7fabd46a89675da596b28bb43c8fd3c561fbe85e
2 files changed