the page address three situations:
1. if the array of requests are all REQUEST_NULL, set flag=true and
index=MPI_UNDEFINED
2. if the array of requests are not all REQUEST_NULL, if any of them
finished, set flag=true and index=whatever_the_index_was
3. if the array of requests are not all REQUEST_NULL, if none of them
finished, set flag=false and index=MPI_UNDEFINED
With regards to the index value, we are currently doing 1 and 2, but
not 3. More specifically, index should be set to MPI_UNDEFINED if no
requests are found to have completed (regardless of whether they are
REQUEST_NULL or not).
This patch fixes this problem.
This commit was SVN r8319.
