fix use-after-free in perf_sched__lat

hulk inclusion
category: bugfix
bugzilla: 14378
CVE: NA

-------------------------------------------------

After thread is added to machine->threads[i].dead in
__machine__remove_thread, the machine->threads[i].dead is freed
when calling free(session) in perf_session__delete(). So it get a
Segmentation fault when accessing it in thread__put().

In this patch, we delay the perf_session__delete until all threads
have been deleted.

This can be reproduced by following steps:
	ulimit -c unlimited
	export MALLOC_MMAP_THRESHOLD_=0
	perf sched record sleep 10
	perf sched latency --sort max
	Segmentation fault (core dumped)

Signed-off-by: Zhipeng Xie <xiezhipeng1@huawei.com>
Signed-off-by: Wei Li <liwei391@huawei.com>
Reviewed-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>