Added limits and a rankdata file.

Added USDT probes.

Added missing MPI_Comm_free() call before MPI_Finalize()

Added an MPI_Barrier() call after MPI_Bcast() for HCOLL issue

Make the -c option be a datacheck iteration count parameter

Default is 1

Add boot_id to the hostname hash due to collisions on Azure

Fixes NVIDIA#60

Call cudaFreeHost() on wrongPerGpu not cudaFree()

Update NCCL tests

Fix preprocessor version check for ncclGetLastError()

ncclGetLastError() was added in NCCL 2.13.0

Fix an issue with the last commit when data checking is disabled