AAPT2: Fix order-of-destruction crash

Make sure that users of StringPool are destroyed before
the StringPool itself.

Test: valgrind aapt2 optimize -o opt.apk out/target/common/obj/APPS/framework-res_intermediates/package-export.apk
Change-Id: I140c2d32f8449028976795d5d6865d83e1409b53
diff --git a/tools/aapt2/xml/XmlDom.cpp b/tools/aapt2/xml/XmlDom.cpp
index 4a278f63..6055190 100644
--- a/tools/aapt2/xml/XmlDom.cpp
+++ b/tools/aapt2/xml/XmlDom.cpp
@@ -224,7 +224,8 @@
 
   XML_ParserFree(parser);
   if (stack.root) {
-    return util::make_unique<XmlResource>(ResourceFile{{}, {}, source}, std::move(stack.root));
+    return util::make_unique<XmlResource>(ResourceFile{{}, {}, source}, StringPool{},
+                                          std::move(stack.root));
   }
   return {};
 }
@@ -357,7 +358,7 @@
       }
     }
   }
-  return util::make_unique<XmlResource>(ResourceFile{}, std::move(root), std::move(string_pool));
+  return util::make_unique<XmlResource>(ResourceFile{}, std::move(string_pool), std::move(root));
 }
 
 std::unique_ptr<Node> Namespace::Clone() {