OPENDJ-1375 CR-4618: prevent deadlocks when updating id2subtree using IndexBuffers

Lock entry ID keys in descending order (children then parents) in order to be
consistent with id2subtree updates performed for single entry add and delete
operations.


git-svn-id: https://svn.forgerock.org/opendj/trunk@11056 41b1ffd8-f28e-4786-ab96-9950f0a78031
Fix issue in method ByteStringBuilder#append(DataInput, int) added in r11047

git-svn-id: https://svn.forgerock.org/opendj/trunk@11058 41b1ffd8-f28e-4786-ab96-9950f0a78031