to let the PML (or io, more generally the low level request manager)
to have it's own release function (what was before the req_fini). This
function will only be called from the low level while the req_free will
be called from the upper level (MPI layer) in order to mark the request
as not used by the user anymore.
From the request point of view the requests will be marked as inactive
everytime we read their status (true for persistent as well). As
MPI_REQUEST_NULL is already marked as inactive, the test and wait functions
are simpler. The drawback is that now we have to change in the
ompi_request_{test|wait} the req_status of the request once we get it's
status.
This commit was SVN r9290.
