This is the source of much of renegotiation's complexity, and of OpenSSL's
implementation of it. In practice, we only care about renegotiation because of
the client auth hack. There, we can safely assume that no server will send
application data between sending the HelloRequest and completing the handshake.
BUG=429450
Change-Id: I37f5abea5fdedb1d53e24ceb11f71287c74bb777
Reviewed-on: https://boringssl-review.googlesource.com/3332
Reviewed-by: Adam Langley <agl@google.com>
e820df9371