File psl-1983/20-kernel/fresh-kernel.ctl artifact c603c0893f part of check-in 6f3f9aca4c

rename 20.SYM PREVIOUS-20.SYM
copy PC:BARE-PSL.SYM 20.SYM
; To regenerate the .CTL files:
; PSL:PSL
; (dskin "20-kernel-gen.sl")