exit: wait: cleanup the ptrace_reparented() checks

exit: wait: cleanup the ptrace_reparented() checks

Now that EXIT_DEAD is the terminal state we can kill "int traced"
variable and check "state == EXIT_DEAD" instead to cleanup the code.  In
particular, this way it is clear that the check obviously doesn't need
tasklist_lock.

Also fix the type of "unsigned long state", "long" was always wrong
although this doesn't matter because cmpxchg/xchg uses typeof(*ptr).

[[email protected]: don't make me google the C Operator Precedence table]
Signed-off-by: Oleg Nesterov <[email protected]>
Cc: Aaron Tomlin <[email protected]>
Cc: "Eric W. Biederman" <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Sterling Alexander <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>