Get SSL 3.0 server tests working.

The missing SSL 3.0 client support in runner.go was fairly minor.

Change-Id: Ibbd440c9b6be99be08a214dec6b93ca358d8cf0a
Reviewed-on: https://boringssl-review.googlesource.com/1516
Reviewed-by: Adam Langley <agl@google.com>