Use SSL_CLIENT_USE_TLS1_2_CIPHERS instead of ssl3_version_from_wire.

The latter was only added after branch point.

Change-Id: I19970478ee301ad85c8f2fb2c76ebde26ebd9887
Reviewed-on: https://boringssl-review.googlesource.com/3250
Reviewed-by: Adam Langley <agl@google.com>