message: [libra_vm] fix min_price_per_gas_unit check log and error format.
  Closes:
  Approved by: tzakian
diff: @@ -178,12 +178,12 @@ impl LibraVM {
  if below_min_bound {
  let error_str = format!(
  "gas unit min price: {}, submitted price: {}",
  - gas_constants.min_transaction_gas_units.get(),
  + gas_constants.min_price_per_gas_unit.get(),
  txn.gas_unit_price()
  );
  warn!(
  "[VM] Gas unit error; min {}, submitted {}",
  - gas_constants.min_transaction_gas_units.get(),
  + gas_constants.min_price_per_gas_unit.get(),
  txn.gas_unit_price()
  );
  return Err(
  