variadic template warning in genreflex prohibits use in CMS build system

The CMS build system runs genreflex with --fail_on_warnings since we had historically found that warnings eventually lead to problems during production.

CMS is now attempting to deploy a new feature which uses variadic templates and requires a ROOT dictionary. However, genreflex issues a warning about a problem that actually does not affect what CMS wishes to do. The problem can be reproduced via

----classes_test.h---

#include <string>

namespace edm {

template <typename... T>

class Table {};

}

-------

---classes_test_def.xml---

<lcgdict>

<class name="edm::Table<float,int,std::string>" />

</lcgdict>

------

Then issue the following command line

/cvmfs/cms-ib.cern.ch/nweek-02487/slc6_amd64_gcc630/lcg/root/6.10.04-akfcbo/bin/genreflex classes_test.h -s classes_test_def.xml -o classes_test_xr.cc --deep --rootmap=classes_test_xr.rootmap --rootmap-lib=dummy.so

[this example used CMS' genreflex but should work with any that also used C++14 when compiling.

We need a suggestion or code change to get around this that does not involve disabling the use of --fail_on_warnings since that has been crucial in the past.