Don't call GetPeerFromOtherThread with thread_list_lock_ held

GetPeerFromOtherThread() may call EnsureFlipFunctionStarted(), which
expects thread_list_lock_ to be not acquired.

Test: art/test/testrunner/testrunner.py --host
Change-Id: Ic19df7aa553a95818f81a265f721baddec90af47
4 files changed