Your Job is safe as per Qatar labor law. But by law, you cannot force employer(old or new) to give you increment until unless explicitly mentioned & agreed in your Authorized employment contract. About NOC, again, by Qatar labor law, you can not force employer to give you NOC to work somewhere else.

below artical from Qatar Labor Law is for your info:-

Article 52
The service contract shall not terminate in any of the following two cases:
1. Death of the employer, unless the contract has been concluded for
consideration related to the person or professional activities of the employer
which cease upon his death.
2. The merger of the enterprise with another enterprise or transfer of its
ownership or the right in its management to a person other than the employer
for any reason.
The successor shall be jointly liable with the former employer for the payment
of the workers entitlements accruing from the latter.