Add diagnostic print to debug agent if it fails to open port

src/debug-agent.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 36 matching lines @@
   const int kOneSecondInMicros = 1000000;
 
   // Allow this socket to reuse port even if still in TIME_WAIT.
   server_->SetReuseAddress(true);
 
   // First bind the socket to the requested port.
   bool bound = false;
   while (!bound && !terminate_) {
     bound = server_->Bind(port_);
 
-    // If an error occoured wait a bit before retrying. The most common error
+    // If an error occurred wait a bit before retrying. The most common error
     // would be that the port is already in use so this avoids a busy loop and
     // make the agent take over the port when it becomes free.
     if (!bound) {
+      PrintF("Failed to open socket on port %d, "
+          "waiting %d ms before retrying\n", port_, kOneSecondInMicros / 1000);
       terminate_now_->Wait(kOneSecondInMicros);
     }
   }
 
   // Accept connections on the bound port.
   while (!terminate_) {
     bool ok = server_->Listen(1);
     listening_->Signal();
     if (ok) {
       // Accept the new connection.
@@ skipping 345 matching lines @@
       return total_received;
     }
     total_received += received;
   }
   return total_received;
 }
 
 } }  // namespace v8::internal
 
 #endif  // ENABLE_DEBUGGER_SUPPORT