8056240: Investigate increased GC remark time after class unloading changes in CRM Fuse

Reviewed-by: mgerdin, coleenp, bdelsart

hotspot/src/share/vm/runtime/thread.cpp

@@ -201,6 +201,8 @@ Thread::Thread() {
   // This initial value ==> never claimed.
   _oops_do_parity = 0;
 
+  _metadata_on_stack_buffer = NULL;
+
   // the handle mark links itself to last_handle_mark
   new HandleMark(this);