If an application opens a file for reading from multiple processes
using MPI_COMM_SELF (or another communicator that has distinct
process groups but the same comm-id, as can happen as the result
of comm_split), the naming chosen for the lockedfile or the mmapped
file used by the sharedfp/sm component would collide. This patch
ensures that the filename is different by integrating the process id
of rank 0 for each sub-communicator.
This fixes one aspect of the problem reported in github issue 5593
Signed-off-by: Edgar Gabriel <egabriel@central.uh.edu>