sched/fair: do not expose some tracepoints to user if CONFIG_SCHEDSTATS is not set

The tracepoints trace_sched_stat_{iowait, blocked, wait, sleep} should
be not exposed to user if CONFIG_SCHEDSTATS is not set.

Link: http://lkml.kernel.org/r/1553602391-11926-3-git-send-email-laoar.shao@gmail.com



Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>