Fix build against Nix master

src/hydra-eval-jobs/hydra-eval-jobs.cc

@@ -195,7 +195,7 @@ int main(int argc, char * * argv)
 
         /* Prevent access to paths outside of the Nix search path and
            to the environment. */
-        settings.restrictEval = true;
+        evalSettings.restrictEval = true;
 
         if (releaseExpr == "") throw UsageError("no expression specified");