SSL_get_psk_identity_hint() is used to retrieve the PSK identity hint
used during the connection setup related to SSL object ssl. Similarly, SSL_get_psk_identity() is used
to retrieve the PSK identity used during the connection setup.
RETURN VALUES
If non-NULL,
SSL_get_psk_identity_hint() returns the PSK identity hint and
SSL_get_psk_identity() returns the PSK identity. Both are NULL-terminated. SSL_get_psk_identity_hint()
may return NULL if no PSK identity
hint was used during the connection setup.
Note that the return value is valid only during the lifetime of the
SSL object ssl.
