add missing includes for the build with use_libcxx_modules

This is to fix build error when we set use_libcxx_modules=true in
chromium build.

Bug: 40263312
Change-Id: I1267f8afea5ea22f66bed9e568da55e975f87457

examples/multilayer_metadata.h

diff --git a/examples/multilayer_metadata.h b/examples/multilayer_metadata.h
index b8601b2..967aaad 100644
--- a/examples/multilayer_metadata.h
+++ b/examples/multilayer_metadata.h
@@ -15,6 +15,7 @@
 #define AOM_EXAMPLES_MULTILAYER_METADATA_H_
 
 #include <cstdint>
+#include <utility>
 #include <vector>
 
 namespace libaom_examples {