Fix initialization order warnings in sorter, block mgr and data stream recvr

Change-Id: I95ea33851a6da7b5ef29f8477ba68084a67af7ae
Reviewed-on: http://gerrit.ent.cloudera.com:8080/2914
Reviewed-by: Srinath Shankar <sshankar@cloudera.com>
Tested-by: jenkins