Don't call exit() while threads may be running

It's unsafe to call exit() in C++ while there are running threads.
The remaining threads would race with static destructors, including
those for the standard library. Call _exit instead.

Bug: 150176543
Test: Boot AOSP, TreeHugger
Change-Id: Ieabf68f43e8b520714643e5ec36a8ca72cc83254
(cherry picked from commit 36896be3815ce0db8dd5f23accfbee24492d7f8a)
2 files changed