Remove a hack from ssl_test_old

ssl_test_old was reaching inside the SSL structure and changing the internal
BIO values. This is completely unneccessary, and was causing an abort in the
test when enabling TLSv1.3.

I also removed the need for ssl_test_old to include ssl_locl.h. This
required the addition of some missing accessors for SSL_COMP name and id
fields.

Reviewed-by: Rich Salz <rsalz@openssl.org>