In hpcstruct, add boost::atomic to the is_done flag for the work lists.  Although very rare, this is a legit data race.
In hpcstruct, add boost::atomic to the is_done flag for the work
lists.  Although very rare, this is a legit data race.

HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit