Change-Id: I7407261bdb2d788c879f2e67e617a615d9ff8f8b
Reviewed-on: https://boringssl-review.googlesource.com/1505
Reviewed-by: Adam Langley <agl@google.com>

Add a framework for testing the asynchronous codepath. Move some handshake
state machine coverage tests to cover a range of record-layer and
handshake-layer asynchronicity.

This adds tests for the previous two async bugs fixed.

Change-Id: I422ef33ba3eeb0ad04766871ed8bc59b677b169e
Reviewed-on: https://boringssl-review.googlesource.com/1410
Reviewed-by: Adam Langley <agl@google.com>