We'll need to maintain two transcripts on the ECH client and then, once
we know which of ClientHelloOuter or ClientHelloInner is used, overwrite
the default transcript with the alternate one.
Rather than indirect through a pointer, move support is easy enough.
Then this can just be hs->transcript = std::move(hs->inner_transcript).
Bug: 275
Change-Id: Id4b0a0a48b956cd65ce8fc3dacfd16eebe2eb778
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/47993
Reviewed-by: Adam Langley <agl@google.com>
David Benjamin
Adam Langley