Only set the flag in the cases when the exit state is not either
TASK_DEAD or TASK_ZOMBIE.

(TASK_DEAD or TASK_ZOMBIE will either race or we'll return the 
information, so no need to note them).

I confirmed that this fixes the problem and I also ran some LTP tests
Signed-off-by: Dinakar Guniguntala <dino@in.ibm.com>
Signed-off-by: Sripathi Kodi <sripathik@in.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>