This commit fixes two bugs in MPI_Wait_any:
- If all requests are inactive then the sync wait would hang forever
because no requests are attached to the sync.
- The request pointer was pointing to the request before the completed
request which caused the wrong request to be freed or marked inactive.
MPI_Wait_some had a similar issue if all the requests were pending.
These issues were identified by MTT.
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>