Don't always enable debug on startup

Improves startup time. Problem introduced in
4ab5476e89

src/node.cc

@@ -2343,13 +2343,6 @@ static void EnableDebug(bool wait_connect) {
 static volatile bool hit_signal;
 
 
-static void EnableDebugSignalHandler(int signal) {
-  // This is signal safe.
-  hit_signal = true;
-  v8::Debug::DebugBreak();
-}
-
-
 static void DebugSignalCB(const Debug::EventDetails& details) {
   if (hit_signal && details.GetEvent() == v8::Break) {
     hit_signal = false;
@@ -2359,6 +2352,14 @@ static void DebugSignalCB(const Debug::EventDetails& details) {
 }
 
 
+static void EnableDebugSignalHandler(int signal) {
+  // This is signal safe.
+  hit_signal = true;
+  v8::Debug::SetDebugEventListener2(DebugSignalCB);
+  v8::Debug::DebugBreak();
+}
+
+
 #ifdef __POSIX__
 
 static int RegisterSignalHandler(int signal, void (*handler)(int)) {
@@ -2480,7 +2481,6 @@ char** Init(int argc, char *argv[]) {
   } else {
 #ifdef __POSIX__
     RegisterSignalHandler(SIGUSR1, EnableDebugSignalHandler);
-    Debug::SetDebugEventListener2(DebugSignalCB);
 #endif // __POSIX__
   }