sched/wait: fix ___wait_var_event(exclusive)

init_wait_var_entry() forgets to initialize wq_entry->flags.

Currently not a problem, we don't have wait_var_event_exclusive().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20191210191902.GB14449@redhat.com

kernel/sched/wait_bit.c

@@ -179,6 +179,7 @@ void init_wait_var_entry(struct wait_bit_queue_entry *wbq_entry, void *var, int
 			.bit_nr = -1,
 		},
 		.wq_entry = {
+			.flags	 = flags,
 			.private = current,
 			.func	 = var_wake_function,
 			.entry	 = LIST_HEAD_INIT(wbq_entry->wq_entry.entry),