Function secp256k1_sys::secp256k1_ec_privkey_negate

pub unsafe extern "C" fn secp256k1_ec_privkey_negate(
    cx: *const Context, 
    sk: *mut c_uchar
) -> c_int

Deprecated since 0.2.0:

Please use the secp256k1_ec_seckey_tweak_add function instead