If we cannot synchronize data access in an APR pool cleanup function,
there is not much we can do except to log the error and to terminate.

Do that in the object pool code.

* subversion/libsvn_subr/object_pool.c
  (exit_on_error): new error checking function
  (object_ref_cleanup): terminate upon sync failure

git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1544027 13f79535-47bb-0310-9956-ffa450edef68