ptrace_stop() releases and regrabs current->sighand->siglock but was
missing proper annotation.  Add it.
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>