Function secp256k1_sys::secp256k1_schnorrsig_sign

pub unsafe extern "C" fn secp256k1_schnorrsig_sign(
    cx: *const Context, 
    sig: *mut c_uchar, 
    msg32: *const c_uchar, 
    keypair: *const KeyPair, 
    noncefp: SchnorrNonceFn, 
    noncedata: *const c_void
) -> c_int