[PATCH] avoid resursive oopses

Prevent recursive faults in do_exit() by leaving the task alone and wait
for reboot.  This may allow a more graceful shutdown and possibly save the
original oops.

Signed-off-by: Alexander Nyberg <alexn@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>