message: gapi: fix build with MSVS2017/2019
diff: @@ -199,7 +199,8 @@ struct GAPI_EXPORTS GNetParam {
  * @sa cv::gapi::networks
  */
  struct GAPI_EXPORTS GNetPackage {
  - explicit GNetPackage(std::initializer_list<GNetParam> &&ii = {});
  + GNetPackage() : GNetPackage({}) {}
  + explicit GNetPackage(std::initializer_list<GNetParam> &&ii);
  std::vector<GBackend> backends() const;
  std::vector<GNetParam> networks;
  };
  