This might be useful for debugging applications that use a special LDT.
However, printing of all segment registers is currently broken.
Don't print "last exception: " before the FPU opcode and pc, etc. The
opcode and pc, etc., are for the last FPU _instruction_.
Pass the saved exception status word to print_387_status() so that the
exception(s) that caused or will cause a trap can be seen. The kernel
has supported this since 1.1 or before. The kernel still clobbers the
tag word if a trap occurs.
Remove unused null function clear_regs().
19bc776351