Added NGRAPH_API for  VariantWrapper (#4732)
Added NGRAPH_API for  VariantWrapper (#4732)

Co-authored-by: gleb.kazantaev <21e5f459fb752922c0b783f5cb09a8321f82e8f3@nncv666el.inn.intel.com>
Co-authored-by: Scott Cyphers <7bb9a997e5f2906b81b1e1515637af43501e2590@users.noreply.github.com>
Co-authored-by: Ashok Emani <4ffc0217af6a2baf137f188a5083a296cc106acc@intel.com>
NervanaSystems/ngraph,NervanaSystems/ngraph,NervanaSystems/ngraph,NervanaSystems/ngraph