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,
    aux_rand32: *const c_uchar
) -> c_int

Available on non-secp256k1_fuzz only.