[Optimize][am_kill]add pss for process exit due to am_kill

There are so many processes in cache or other priority exit due to
am_kill, such as OnekeyClean, swipeup clean and so on. This processes
exit without pss can not show develop how much memory it can free.

Process which kill by lmkd can show memory detail, this patch aim to
have same effect with lmkd. If one abnormal memory using process exit, it can tell develop this process may have problem so develop can do something for this terrible process.

BUG:318323015

Signed-off-by:  <xueguolun@xiaomi.corp-partner.google.com>
Change-Id: Ie0f9d599fc929d3055038f9a28e21b95e17fec38