Function secp256k1::ffi::secp256k1_ecdsa_sign

pub unsafe fn secp256k1_ecdsa_sign(
    cx: *const Context, 
    sig: *mut Signature, 
    msg32: *const u8, 
    sk: *const u8, 
    _noncefn: NonceFn, 
    _noncedata: *const c_void
) -> i32

Sets sig to msg32||sk