message: fix simple-solver-logging example
  Since we made Dense::convert_to(Dense) a kernel call,
  the example no longer involves and copy operations,
  so the vector is empty.
diff: @@ -165,16 +165,7 @@ int main(int argc, char* argv[])
  // Solve system
  solver->apply(lend(b), lend(x));
  - // Finally, get some data from `record_logger` and print the last memory
  - // location copied
  - auto& last_copy = record_logger->get().copy_completed.back();
  - std::cout << "Last memory copied was of size " << std::hex
  - << std::get<0>(*last_copy).num_bytes << " FROM executor "
  - << std::get<0>(*last_copy).exec << " pointer "
  - << std::get<0>(*last_copy).location << " TO executor "
  - << std::get<1>(*last_copy).exec << " pointer "
  - << std::get<1>(*last_copy).location << std::dec << std::endl;
  - // Also print the residual of the last criterion check event (where
  + // Print the residual of the last criterion check event (where
  // convergence happened)
  auto residual =
  record_logger->get().criterion_check_completed.back()->residual.get();
  