[ros-diffs] [sginsberg] 44063: - Add KCALLOUT_FRAME to define the kernel callback stack layout during user mode callbacks. Define the NextCallback and FramePointer members of the debugger data block more portably with this. - AMD64's is a copy of x86's to match asm.h's the assembly offsets. ARM's is a stub containing two necessary members to have some offsets for the debugger data block. - Add ARM stub for KiCallUserMode as this is referenced from the debugger data block.