Remove old reentrancy example

solidity_examples/reentrancy.sol

@@ -1,22 +0,0 @@
-contract Reentrancy {
-
-  mapping(address => uint) public balances;
-
-  function donate(address _to) public payable {
-    balances[_to] += msg.value;
-  }
-
-  function balanceOf(address _who) public constant returns (uint balance) {
-    return balances[_who];
-  }
-
-  function withdraw(uint _amount) public {
-    if(balances[msg.sender] >= _amount) {
-      if (msg.sender.call.value(_amount)()) {
-        balances[msg.sender] -= _amount;        
-      }
-    }
-  }
-
-  function() payable {}
-}