MFC r280323: Somewhat modernize the SysV shm code.
MFC r280323:
Somewhat modernize the SysV shm code.

MFC r280325 (by cognet):
Fix warning for !MAC case.

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