DER encode content of ECDSA_SIG object (note: this function modifies* pp
(*pp += length of the DER encoded signature)).
\param sig pointer to the ECDSA_SIG object
\param pp pointer to a ubyte pointer for the output or NULL
\return the length of the DER encoded ECDSA_SIG object or 0
DER encode content of ECDSA_SIG object (note: this function modifies* pp (*pp += length of the DER encoded signature)). \param sig pointer to the ECDSA_SIG object \param pp pointer to a ubyte pointer for the output or NULL \return the length of the DER encoded ECDSA_SIG object or 0