Fix the debug output - you can't print the cpuset pointer using the %p format without generating warnings
ompi_info_get_bool returns "success" if the value isn't found, setting "flag" to false, but doesn't set the value of the param itself. So if you don't specify "blocking_fence" in MPI_Info, then the "blocking_fence" flag wasn't being set.

Initialize the blocking_fence flag to false as the code logic indicates that it should only be set if someone provides that flag.

Thanks to Lisandro Dalcin for reporting it

cmr=v1.8.4:reviewer=hjelmn