Avoid unnecessary copies of PhoneMetadata

The PhoneMetadata can be moved into the hashmap avoiding a copy.

cpp/src/phonenumbers/shortnumberinfo.cc

@@ -52,9 +52,9 @@ ShortNumberInfo::ShortNumberInfo()
     LOG(DFATAL) << "Could not parse compiled-in metadata.";
     return;
   }
-  for (const auto& metadata : metadata_collection.metadata()) {
-    const string& region_code = metadata.id();
-    region_to_short_metadata_map_->insert(std::make_pair(region_code, metadata));
+  for (auto& metadata : *(metadata_collection.mutable_metadata())) {
+    const string region_code = metadata.id();
+    region_to_short_metadata_map_->emplace(region_code, std::move(metadata));
   }
   regions_where_emergency_numbers_must_be_exact_->insert("BR");
   regions_where_emergency_numbers_must_be_exact_->insert("CL");