Dump more debug info for b/33006388.

Bug: 33006388
Bug: 12687968
Test: test-art-host with CC.
Change-Id: Id9d67bc603c6ff7bc8e346e181e3e09ffbda43b3
diff --git a/runtime/barrier.cc b/runtime/barrier.cc
index 0d842cc..9bcda35 100644
--- a/runtime/barrier.cc
+++ b/runtime/barrier.cc
@@ -80,6 +80,11 @@
   return timed_out;
 }
 
+int Barrier::GetCount(Thread* self) {
+  MutexLock mu(self, lock_);
+  return count_;
+}
+
 void Barrier::SetCountLocked(Thread* self, int count) {
   count_ = count;
   if (count == 0) {