debugger: exit process on repl exit

* When entering repl - clone 'SIGINT' listeners array (instead of using
existing), as it will be spliced in .removeAllListeners() call later.

lib/_debugger.js

@@ -755,6 +755,10 @@ function Interface(stdin, stdout, args) {
                                   this.controlEval.bind(this), false, true);
 
   // Kill child process when main process dies
+  this.repl.on('exit', function() {
+    process.exit(0);
+  });
+
   process.on('exit', function() {
     self.killChild();
   });
@@ -1486,7 +1490,7 @@ Interface.prototype.repl = function() {
   self.print('Press Ctrl + C to leave debug repl');
 
   // Don't display any default messages
-  var listeners = this.repl.rli.listeners('SIGINT');
+  var listeners = this.repl.rli.listeners('SIGINT').slice(0);
   this.repl.rli.removeAllListeners('SIGINT');
 
   // Exit debug repl on Ctrl + C