Let statemachine honor approvements.

The inventory bulk fetch is not thread-safe, so the it doesn't start
right away, causing the approvement not to be honored upon return from
post_approved (formerly post_nb).

This patch renames wantsMoreHTTPReqestsFor to approveHTTPRequestFor,
and has it return NULL or a AIPerService::Approvement object.
The latter is now passed to the CurlEasyHandle object instead of just a
boolean mQueueIfTooMuchBandwidthUsage, and then the Approvement is
honored by the state machine right after the request is actually added
to the command queue.

This should avoid a flood of inventory requests in the case
approveHTTPRequestFor is called multiple times before the main thread
adds the requests to the command queue. I don't think that actually ever
happens, but I added debug code (to find some problem) that is so damn
strictly checking everything that I need to be this precise in order to
do that testing.

indra/llmessage/llurlrequest.h

@@ -66,7 +66,8 @@ class LLURLRequest : public AICurlEasyRequestStateMachine {
 	 */
 	LLURLRequest(ERequestAction action, std::string const& url, Injector* body,
 				 LLHTTPClient::ResponderPtr responder, AIHTTPHeaders& headers,
-				 bool keepalive, bool is_auth, bool no_compression, bool queue_if_too_much_bandwidth_usage);
+				 AIPerService::Approvement* approved,
+				 bool keepalive, bool is_auth, bool no_compression);
 
 	/**
 	 * @brief Cached value of responder->getName() as passed to the constructor.