Fix thread hang

- Primary problem was ScopedThreadListLock was releasing heap lock in constructor instead of destructor
- Secondary problem was ScopedThreadListLock should not be used with Mutex::Wait
- Added Thread.getStackTrace case to ThreadStress that reproduces YouTube problem
- Added Mutex::GetDepth and related methods that were useful in diagnoising this issue

Change-Id: I1bdc7245e9b411378b98f4dcf498ad66eb96366d
diff --git a/build/Android.common.mk b/build/Android.common.mk
index a404231..a7f0037 100644
--- a/build/Android.common.mk
+++ b/build/Android.common.mk
@@ -239,6 +239,7 @@
 	src/jni_compiler_test.cc \
 	src/managed_register_arm_test.cc \
 	src/managed_register_x86_test.cc \
+	src/mutex_test.cc \
 	src/oat_test.cc \
 	src/object_test.cc \
 	src/reference_table_test.cc \