On the fsfs-format7 branch:  Fix item index counter storage.

* subversion/libsvn_fs_fs/transaction.c
  (allocate_item_index): use the correct buffer size value

git-svn-id: https://svn.apache.org/repos/asf/subversion/branches/fsfs-format7@1438417 13f79535-47bb-0310-9956-ffa450edef68