Because we can encounter pending interrupts repeatedly,
HalpEndSoftwareInterrupt and HalEndSystemInterrupt already clean up the stack
space for their arguments (done for CORE-11123/CORE-14076).
However these functions are called from C functions such as KiInterruptDispatch
and HalpDispatchInterrupt2[ndEntry]. These callers also use up stack space,
and it is unknown how much.
To fix this, we simply reset the stack pointer to the location of the trap
frame, which is where it points during a first-level dispatch. This cleans
up the stack usage of any callers higher up, and is okay because a return
will happen through the trap frame anyway.
Dedicated to Pierre.
