Switch to side-by-side view

--- a/upmpd/ohvolume.cxx
+++ b/upmpd/ohvolume.cxx
@@ -98,9 +98,9 @@
     }
     m_state = state;
 
-    for (auto& member : changed) {
-        names.push_back(member.first);
-        values.push_back(member.second);
+    for (auto it = changed.begin(); it != changed.end(); it++) {
+        names.push_back(it->first);
+        values.push_back(it->second);
     }
 
     return true;