Use signed char cast to avoid out-of-range error on PowerPC (which has unsigned char by default). This is a no-op on all other current arches.
Use signed char cast to avoid out-of-range error on PowerPC (which has
unsigned char by default). This is a no-op on all other current arches.

Tested by: md5 sum before/after same on i386

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