Improve usage of tunefs:
Improve usage of tunefs:

Document -j switch in usage() to reflect recent SUJ work.

Submitted by:   Alastair Hogge
MFC after:      1 week

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase