(5) Nothing herein contained shall be deemed to confer any right to compensation on a workman in respect of any injury if he has instituted in a Civil Court a suit for damages in respect of the injury against the employer or any other person; and no suit for damages shall be maintainable by a workman in any Court of law in respect of any injury--
(a) if he has instituted a claim to compensation in respect of the injury before a Commissioner; or
(b) if an agreement has been come to between the workman and his employer providing for the payment of compensation in respect of the injury in accordance with the provisions of this Act.