tracing/fgraph: Have wakeup and irqsoff tracers ignore graph functions too

Currently both the wakeup and irqsoff traces do not handle set_graph_notrace
well. The ftrace infrastructure will ignore the return paths of all
functions leaving them hanging without an end:

  # echo '*spin*' > set_graph_notrace
  # cat trace
  [...]
          _raw_spin_lock() {
            preempt_count_add() {
            do_raw_spin_lock() {
          update_rq_clock();

Where the '*spin*' functions should have looked like this:

          _raw_spin_lock() {
            preempt_count_add();
            do_raw_spin_lock();
          }
          update_rq_clock();

Instead, have the wakeup and irqsoff tracers ignore the functions that are
set by the set_graph_notrace like the function_graph tracer does. Move
the logic in the function_graph tracer into a header to allow wakeup and
irqsoff tracers to use it as well.

Cc: Namhyung Kim <namhyung.kim@lge.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>