We have a special file, tag.h, which serves as a place to store whatever kernel pool allocation tag yet we still have some tags sparse over the kernel code... So just re-group them in one unique place.
The trap frame is in a random location on the stack, and setting Esp0 there
wastes significant amounts of space and may lead to unexpected stack overflows.
Also use a more descriptive expression for the V86 members of the KTRAP_FRAME.
