Move signal_watcher to extension model.

src/node.cc

@@ -1597,10 +1597,6 @@ static Handle<Value> Binding(const Arguments& args) {
     StatWatcher::Initialize(exports);
     File::Initialize(exports);
     binding_cache->Set(module, exports);
-  } else if (!strcmp(*module_v, "signal_watcher")) {
-    exports = Object::New();
-    SignalWatcher::Initialize(exports);
-    binding_cache->Set(module, exports);
   } else if (!strcmp(*module_v, "http_parser")) {
     exports = Object::New();
     InitHttpParser(exports);

src/node_extensions.h

@@ -5,6 +5,7 @@ NODE_EXT_LIST_ITEM(node_cares)
 NODE_EXT_LIST_ITEM(node_crypto)
 #endif
 NODE_EXT_LIST_ITEM(node_net)
+NODE_EXT_LIST_ITEM(node_signal_watcher)
 NODE_EXT_LIST_ITEM(node_stdio)
 NODE_EXT_LIST_END
 

src/node_signal_watcher.cc

@@ -96,3 +96,5 @@ void SignalWatcher::Stop () {
 }
 
 }  // namespace node
+
+NODE_MODULE(node_signal_watcher, node::SignalWatcher::Initialize);