Change intern table to not use WaitHoldingLocks

Bug: 22423014
Change-Id: I9e16b8cb4def72fff73f1783a182877105feb7aa
diff --git a/runtime/gc/collector/mark_sweep.cc b/runtime/gc/collector/mark_sweep.cc
index 4035143..abb1d3d 100644
--- a/runtime/gc/collector/mark_sweep.cc
+++ b/runtime/gc/collector/mark_sweep.cc
@@ -1006,7 +1006,7 @@
 
 void MarkSweep::SweepSystemWeaks(Thread* self) {
   TimingLogger::ScopedTiming t(__FUNCTION__, GetTimings());
-  WriterMutexLock mu(self, *Locks::heap_bitmap_lock_);
+  ReaderMutexLock mu(self, *Locks::heap_bitmap_lock_);
   Runtime::Current()->SweepSystemWeaks(this);
 }