This was changed in draft-ietf-quic-tls-13 to use a codepoint from the
reserved range.

Change-Id: Ia3cda249a3f37bc244d5c8a7765ec34a5708c9ae
Reviewed-on: https://boringssl-review.googlesource.com/29464
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>