Possibly fixes CID 417
* ensure to initialize inner members upon default constructors using
the same syntax across all classes
* remove some member variables that aren't used anymore
* "initialize" the inner MPI_Status in the default constructor for
MPI::Status by calling the default constructor mpi_status(). This
may or may not silence CID 417; we'll see what happens in
subsequent Coverity Prevent runs.
This commit was SVN r19228.
fa25de320e