Function secp256k1::ffi::secp256k1_ecdsa_sign_recoverable

pub unsafe fn secp256k1_ecdsa_sign_recoverable(
    cx: *const Context, 
    sig: *mut RecoverableSignature, 
    msg32: *const c_uchar, 
    sk: *const c_uchar, 
    _noncefn: NonceFn, 
    _noncedata: *const c_void
) -> c_int

Sets sig to (2|3)||msg32||sk