Detect over-long thread suspends and time out fatally.

Bug: 5726434
Change-Id: Ib7d4429c2b195f59133bb6dc7f9072b705c53e82
diff --git a/src/runtime.h b/src/runtime.h
index 1d9a3d1..80534c2 100644
--- a/src/runtime.h
+++ b/src/runtime.h
@@ -119,6 +119,7 @@
   void DetachCurrentThread();
 
   void Dump(std::ostream& os);
+  void DumpLockHolders(std::ostream& os);
 
   ~Runtime();