Upgrading Majority.sol to solidity v0.5

src/Majority.sol

 // Robert Martin-Legene <robert@nic.ar>
 // vim:syntax:filetype=javascript:ai:sm
 
-pragma solidity ^0.4.24;
+pragma solidity ^0.5;
 
 // This contract is supposed to maintain a list of accounts authorized
 // to control members of "the club" using a majority (n/1+1).
@@ -28,7 +28,9 @@ contract Majority {
 
     constructor() public
     {
-        voters.push( msg.sender );
+        // Don't want anyone to find a way to trigger the constructor again.
+        if ( voters.length == 0 )
+            voters.push( msg.sender );
     }
 
     // This function is used to know how many voters exist.
@@ -55,7 +57,7 @@ contract Majority {
     // Beware that:
     // 0 = not found.
     // 1 = first position in a list (so this is actually the real list position + 1).
-    function    _findAddressInList( address[] haystack, address needle ) private pure returns (uint)
+    function    _findAddressInList( address[] memory haystack, address needle ) private pure returns (uint)
     {
         uint    i   =   haystack.length;
         while ( i-- > 0 )