Let SSL_copy_session_id() return an int for error checking.

Let SSL_copy_session_id() return an int for error checking.

Accordingly, add some error checking to SSL_copy_session_id(),
BIO_ssl_copy_session_id(), and SSL_dup().
Prompted by OpenSSL commit 17dd65e6e1f

Tested in a bulk build by sthen

ok jsing