Get rid of ssl_undefined_*

The only place using it is export keying material which can do the
version check inline.

Change-Id: I1893966c130aa43fa97a6116d91bb8b04f80c6fb
Reviewed-on: https://boringssl-review.googlesource.com/4615
Reviewed-by: Adam Langley <agl@google.com>
6 files changed