If a panic occurs from a BIOS call (16 bit mode) or VM86 DDB will attempt

If a panic occurs from a BIOS call (16 bit mode) or VM86 DDB will attempt
to disassemble the instruction @ eip.  The problem is that eip is not a
valid KVM address since it is relative to a different %cs selector.  This
commit causes DDB to make appropriate conversions when accessing %eip,
%esp, and %ebp.