Backstop Syndicate for MakerDAO security record

Constructors do not check if provided arguments are non-zero values. The deployed code, however, has been initialized with correct values. Hence, the issue is only informational; otherwise would have been of **low severity**.

A reentrancy vulnerability is a scenario where an attacker can repeatedly call a function from itself, unexpectedly leading to potentially disastrous results. Here's a basic example representing the very attack which impacted The DAO in 2016: ``` function withdraw_with_reentrancy(uint256 _amount) public { msg.sender.call.value(_amount)(); // ATTACKER CAN CALL AGAIN BEFORE // FUNCTION TERMINATES because `call` // allows msg.sender to execute any code using fallback function balances[msg.sender] -= _amount; // Balance only updated AFTER funds withdrawn } ``` Possible re-entrancy occurs in lines 93, 98, 186. The deployed code, however, has been initialized with addresses that refer to Maker's contracts. These contracts do not cause re-entrancy, hence, the issue is only informational; otherwise could have been of **high severity**.

The function `EnumerableSet.contains()` may return different values depending on whether it is ordered before or after a transaction that executes `EnumerableSet.remove()` for the same value in the same block. Consequently, there is a similar transaction order dependence between the functions `DaiBackstopSyndicate.enterAuction()` and `DaiBackstopSyndicate.finalizeAuction()`.