Fixed and adjusted remainders of isValid() code.

Note that in the code, and still, has_curl_request was always false.
However, instead of deleting all code paths that are only executed
when has_curl_request would be true, I fixed the code to work as
intended with my current implementation; which also results in
LLCurlRequests to never expire. This way things won't break
unexpectedly when this ever changes.

Since on this branch isValid was only called still (the rest was
removed already) to check if the curl download expired, I took
the liberty to rename isValid to hasNotExpired.

indra/llmessage/aicurlprivate.h

@@ -318,6 +318,10 @@ class CurlResponderBuffer : protected AICurlEasyHandleEvents {
   public:
 	// Return pointer to the ThreadSafe (wrapped) version of this object.
 	ThreadSafeBufferedCurlEasyRequest* get_lockobj(void);
+
+	// Return true when prepRequest was already called and the object has not been
+	// invalidated as a result of calling timed_out().
+	bool isValid(void) const { return mResponder; }
 };
 
 // This class wraps CurlEasyRequest for thread-safety and adds a reference counter so we can
@@ -333,6 +337,8 @@ class ThreadSafeCurlEasyRequest : public AIThreadSafeSimple<CurlEasyRequest> {
 	virtual ~ThreadSafeCurlEasyRequest()
 	    { Dout(dc::curl, "Destructing ThreadSafeCurlEasyRequest with this = " << (void*)this); }
 
+	/*virtual*/ bool isBuffered(void) const { return false; }
+
   private:
 	LLAtomicU32 mReferenceCount;
 
@@ -351,6 +357,8 @@ class ThreadSafeBufferedCurlEasyRequest : public ThreadSafeCurlEasyRequest, publ
   public:
 	// Throws AICurlNoEasyHandle.
 	ThreadSafeBufferedCurlEasyRequest(void) { new (AIThreadSafeSimple<CurlResponderBuffer>::ptr()) CurlResponderBuffer; }
+
+	/*virtual*/ bool isBuffered(void) const { return true; }
 };
 
 // The curl easy request type wrapped in a reference counting pointer.