This makes any ptrace operation that finds the target in TASK_STOPPED state
morph it into TASK_TRACED state before doing anything.  This necessitates
reverting the last_siginfo accesses to check instead of assume last_siginfo
is set, since it's no longer impossible to be in TASK_TRACED without being
stopped in ptrace_stop (though there are no associated races to worry
about).
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>