message: Update the error message in LinearForm::Assemble for the case of
  boundary face integrators.
diff: @@ -137,7 +137,7 @@ void LinearForm::Assemble()
  }
  Array<int> &bdr_marker = *flfi_marker[k];
  MFEM_ASSERT(bdr_marker.Size() == bdr_attr_marker.Size(),
  - "invalid boundary marker for boundary integrator #"
  + "invalid boundary marker for boundary face integrator #"
  << k << ", counting from zero");
  for (int i = 0; i < bdr_attr_marker.Size(); i++)
  {
  