message: G-API: Recent inclusion has broken STANDALONE build
  This MR fixes this.
diff: @@ -94,8 +94,12 @@ void bindInArg(Mag& mag, const RcDesc &rc, const GRunArg &arg, bool is_umat)
  case GRunArg::index_of<cv::gapi::own::Mat>() :
  if (is_umat)
  {
  +#if !defined(GAPI_STANDALONE)
  auto& mag_umat = mag.template slot<cv::UMat>()[rc.id];
  mag_umat = to_ocv(util::get<cv::gapi::own::Mat>(arg)).getUMat(ACCESS_READ);
  +#else
  + util::throw_error(std::logic_error("UMat is not supported in stadnalone build"));
  +#endif // !defined(GAPI_STANDALONE)
  }
  else
  {
  @@ -157,8 +161,12 @@ void bindOutArg(Mag& mag, const RcDesc &rc, const GRunArgP &arg, bool is_umat)
  case GRunArgP::index_of<cv::gapi::own::Mat*>() :
  if (is_umat)
  {
  +#if !defined(GAPI_STANDALONE)
  auto& mag_umat = mag.template slot<cv::UMat>()[rc.id];
  mag_umat = to_ocv(*(util::get<cv::gapi::own::Mat*>(arg))).getUMat(ACCESS_RW);
  +#else
  + util::throw_error(std::logic_error("UMat is not supported in standalone build"));
  +#endif // !defined(GAPI_STANDALONE)
  }
  else
  {
  @@ -256,7 +264,13 @@ cv::GRunArgP getObjPtr(Mag& mag, const RcDesc &rc, bool is_umat)
  {
  case GShape::GMAT:
  if (is_umat)
  + {
  +#if !defined(GAPI_STANDALONE)
  return GRunArgP(&mag.template slot<cv::UMat>()[rc.id]);
  +#else
  + util::throw_error(std::logic_error("UMat is not supported in standalone build"));
  +#endif // !defined(GAPI_STANDALONE)
  + }
  else
  return GRunArgP(&mag.template slot<cv::gapi::own::Mat>()[rc.id]);
  case GShape::GSCALAR: return GRunArgP(&mag.template slot<cv::gapi::own::Scalar>()[rc.id]);
  @@ -300,8 +314,12 @@ void writeBack(const Mag& mag, const RcDesc &rc, GRunArgP &g_arg, bool is_umat)
  }
  if (is_umat)
  {
  +#if !defined(GAPI_STANDALONE)
  auto& in_mag = mag.template slot<cv::UMat>().at(rc.id);
  GAPI_Assert((out_arg_data == (in_mag.getMat(ACCESS_RW).data)) && " data for output parameters was reallocated ?");
  +#else
  + util::throw_error(std::logic_error("UMat is not supported in standalone build"));
  +#endif // !defined(GAPI_STANDALONE)
  }
  else
  {
  