Fix build on GCC 7.3.1. (#10)

Author: teo

Framework/src/TObject2JsonFactory.cxx

@@ -19,6 +19,8 @@
 #include "TObject2JsonCcdb.h"
 #include "external/UriParser.h"
 
+#include <functional>
+
 namespace o2 {
 namespace quality_control {
 namespace tobject_to_json {