As of Node 0.9.1 use of NODE_MODULE in an extension is required.

We'd been getting away without a NODE_MODULE(...) declaration in
this module, but in Node 0.9.1 the legacy "scan for init" mechanism
went away.

This change adds the required declaration, and the extension now
builds on 0.9.1+.

dtrace_provider.cc

@@ -190,4 +190,5 @@ namespace node {
     DTraceProvider::Initialize(target);
   }
 
+  NODE_MODULE(DTraceProviderBindings, init)
 } // namespace node