epoch's control data could overwrite the previous epoch's data because
we were reusing data structures between PW and SC. Instead, we now
have explicit post_msg and complete_msg counters for completion.
refs trac:354
* Only register the rdma osc callback once, as it turns out that some
btls (MX) do somethng more than update a table during the register
call, and each register call sucks up valuable fragments...
This commit was SVN r11745.
The following Trac tickets were found above:
Ticket 354 --> https://svn.open-mpi.org/trac/ompi/ticket/354