Now that we have a separate header file for sigset_t, use it and avoid the full pollution of <signal.h>.
Now that we have a separate header file for sigset_t, use it and avoid
the full pollution of <signal.h>.

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