Change HANDSHAKE_STATE to OSSL_HANDSHAKE_STATE

Change HANDSHAKE_STATE to OSSL_HANDSHAKE_STATE

Rename the enum HANDSHAKE_STATE to OSSL_HANDSHAKE_STATE to ensure there are
no namespace clashes, and convert it into a typedef.

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>