spl.h: Don't calculate imask for splstatclock() every call.
spl.h:
Don't calculate imask for splstatclock() every call.

Remove declaration of nonexistent variable `high_imask'.

Sort declarations of imasks and spl's.

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