Merge branch 'avoid-temporaries' into 'master'

Avoid tempories in a range-based for loop

See merge request !814

common/ParameterRecord.cc

@@ -13,7 +13,7 @@ namespace common {
 std::ostream& operator<<(std::ostream& os, const ParameterRecord& record) {
   bool first = true;
   os << '{';
-  for (const std::pair<std::string, ParameterValue>& entry : record) {
+  for (const std::pair<const std::string, ParameterValue>& entry : record) {
     if (first) {
       first = false;
     } else {

common/ParameterSet.cc

@@ -71,7 +71,7 @@ blob::BlobOStream& operator<<(blob::BlobOStream& stream,
                               const ParameterSet& set) {
   stream.putStart("ParameterSet", 1);
   stream << static_cast<std::uint32_t>(set.size());
-  for (const std::pair<std::string, ParameterValue>& entry : set) {
+  for (const std::pair<const std::string, ParameterValue>& entry : set) {
     stream << entry.first << entry.second.get();
   }
   stream.putEnd();