Fix build. ART mandates the ordering of fields in SIRT.

Change-Id: I3ea8e165d9598b35045d895caf04a276a6c50576
diff --git a/src/stack_indirect_reference_table.h b/src/stack_indirect_reference_table.h
index 77cbddc..5c6bc0a 100644
--- a/src/stack_indirect_reference_table.h
+++ b/src/stack_indirect_reference_table.h
@@ -88,14 +88,13 @@
  private:
   StackIndirectReferenceTable() {}
 
+  size_t number_of_references_;
   StackIndirectReferenceTable* link_;
 #if defined(ART_USE_LLVM_COMPILER)
   Object* method_;
   uint32_t line_num_;
 #endif
 
-  size_t number_of_references_;
-
   // number_of_references_ are available if this is allocated and filled in by jni_compiler.
   Object* references_[1];