Gets the affine coordinates of a EC_POINT over GFp
\param group underlying EC_GROUP object
\param p EC_POINT object
\param x BIGNUM for the x-coordinate
\param y BIGNUM for the y-coordinate
\param ctx BN_CTX object (optional)
\return 1 on success and 0 if an error occured
Gets the affine coordinates of a EC_POINT over GFp \param group underlying EC_GROUP object \param p EC_POINT object \param x BIGNUM for the x-coordinate \param y BIGNUM for the y-coordinate \param ctx BN_CTX object (optional) \return 1 on success and 0 if an error occured