Correctly add the QueueID to a pending block's extended thread backtrace thread.
Seed the QueueItem objects with the item_refs and addresses when they are fetched
in one batch.  If additional information is needed from the QueueItem, fetch it
lazily one pending item per function call.
<rdar://problem/16270007>, <rdar://problem/16032150> 


git-svn-id: https://llvm.org/svn/llvm-project/lldb/trunk@203449 91177308-0d34-0410-b5e6-96231b3b80d8