Re-enable SSLv2 support to restore ABI.
Excerpt from CHANGES:
Even if "enable-ssl2" is used, users who want to negotiate SSLv2 via the version-flexible SSLv23_method() will need to explicitly call either of:
SSL_CTX_clear_options(ctx, SSL_OP_NO_SSLv2);
or
SSL_clear_options(ssl, SSL_OP_NO_SSLv2);
as appropriate. Even if either of those is used, or the application explicitly uses the version-specific SSLv2_method() or its client and server variants, SSLv2 ciphers vulnerable to exhaustive search key recovery have been removed. Specifically, the SSLv2 40-bit EXPORT ciphers, and SSLv2 56-bit DES are no longer available.
Approved by: re (marius, gjb), so (delphij)