Do not destruct running Responders upon viewer exit.

This hopefully saves some crashes.

indra/aistatemachine/aistatemachine.h

@@ -308,6 +308,7 @@ class AIStateMachine : public LLThreadSafeRefCount
 	virtual void abort_impl(void) { }
 	virtual void finish_impl(void) { }
 	virtual char const* state_str_impl(state_type run_state) const = 0;
+	virtual void force_killed(void);										// Called from AIEngine::flush().
 
   private:
 	void reset(void);														// Called from run() to (re)initialize a (re)start.
@@ -324,7 +325,6 @@ class AIStateMachine : public LLThreadSafeRefCount
 		mSleep = 0;
 	  return mSleep != 0;
 	}
-	void force_killed(void);												// Called from AIEngine::flush().
 
 	friend class AIEngine;						// Calls multiplex() and force_killed().
 };

indra/llmessage/llurlrequest.cpp

@@ -146,6 +146,18 @@ void LLURLRequest::initialize_impl(void)
 	}
 }
 
+void LLURLRequest::force_killed(void)
+{
+	// Avoid destructing the responder, if any, because that might
+	// execute code that might crash now that the viewer is exiting.
+	if (mResponder)
+	{
+		intrusive_ptr_add_ref(mResponder.get());
+	}
+	// Call base class.
+	AIStateMachine::force_killed();
+}
+
 void LLURLRequest::addHeader(const char* header)
 {
 	AICurlEasyRequest_wat curlEasyRequest_w(*mCurlEasyRequest);

indra/llmessage/llurlrequest.h

@@ -118,6 +118,9 @@ class LLURLRequest : public AICurlEasyRequestStateMachine {
   protected:
 	// Handle initializing the object.
 	/*virtual*/ void initialize_impl(void);
+
+	// Called when statemachine was flushed (and killed) at viewer exit.
+	/*virtual*/ void force_killed(void);
 };
 
 #endif // LL_LLURLREQUEST_H