Move all the bssl_shim handshake checks to their own function.

DoExchange is getting unwieldy.

Change-Id: I4eae6eb7471d1bb53b5305191dd9c52bb097a24f
Reviewed-on: https://boringssl-review.googlesource.com/5172
Reviewed-by: Adam Langley <agl@google.com>
1 file changed