Fix a client API rule violation in 'svn import'.

* subversion/libsvn_client/import.c
  (svn_client_import5): A commit item's path is supposed to be absolute
   so set item->path to the already calculated absolute path.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1623974 13f79535-47bb-0310-9956-ffa450edef68