8275607: G1: G1CardSetAllocator::drop_all needs to call G1SegmentedArray::drop_all

Reviewed-by: tschatzl, ayang

src/hotspot/share/gc/g1/g1CardSetMemory.cpp

@@ -114,6 +114,7 @@ void G1CardSetAllocator<Elem>::drop_all() {
   _pending_nodes_list.pop_all();
   _num_pending_nodes = 0;
   _num_free_nodes = 0;
+  _segmented_array.drop_all();
 }
 
 template <class Elem>