- Fix for the x86_64 backtrace code to search all of the exception
  stacks for the origin of the active tasks' backtrace when the
  information is not available in the dumpfile header.  Up until now,
  the search was made in the process stack, the per-cpu IRQ stack,
  and the per-cpu NMI exception stack; this patch looks at all 3
  exception stacks in 2.4 kernels (NMI, STACKFAULT and DOUBLEFAULT),
  and all 5 exception stacks in 2.6 kernels (NMI, STACKFAULT,
  DOUBLEFAULT, DEBUG and MCE).
- Fix to remove erroneous warning message re: the task cpu not being
  the same as the IRQ or exception stack cpu, which was displayed when
  doing a non-context-sensitive "bt -E" on an x86_64.