Perform SetEvent under the user_code_suspend_count_lock_

We would perform major parts of SetEvent without any synchronization
and perform multiple internal suspensions. This could lead to
inconsistent state or deadlocks.

Test: ./test.py --host
Test: ./art/tools/run-libjdwp-tests.sh --mode=host

Change-Id: Ice2fc94b4f82fcd5938928e8dbf1bdddd29000ab
4 files changed