Avoid unnecessary sign extension when promoted to a 64-bit integer.
Avoid unnecessary sign extension when promoted to a 64-bit integer.

This was benign because the interruption info field is a 32-bit quantity and
the hardware guarantees that the upper 32-bits are all zeros. But it did make
reading the objdump output very confusing.

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