Add throttling to HTTP inventory (bulk) fetching.

Call AIPerService::wantsMoreHTTPRequestsFor in
LLInventoryModelBackgroundFetch::bulkFetch to determine if curl is ready
for the next batch or not, instead of using inaccurate heuristic code
that is just guessing a bit.

indra/newview/llinventorymodelbackgroundfetch.h

@@ -29,6 +29,7 @@
 
 #include "llsingleton.h"
 #include "lluuid.h"
+#include "aicurlperservice.h"
 
 //~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 // Class LLInventoryModelBackgroundFetch
@@ -81,6 +82,8 @@ private:
 	BOOL mTimelyFetchPending;
 	S32  mNumFetchRetries;
 
+	AIPerServicePtr mPerServicePtr;		// Pointer to the AIPerService corresponding to the FetchInventory2 capability.
+
 	LLFrameTimer mFetchTimer;
 	F32 mMinTimeBetweenFetches;
 	F32 mMaxTimeBetweenFetches;