DRMWorkaround: Skip workaround on OpenJDK.

[schildbach]

According to https://stackoverflow.com/questions/1179672/how-to-avoid-installing-unlimited-strength-jce-policy-files-when-deploying-an the workaround is not needed on OpenJDK.

@oscarguindzberg What do you think?

[oscarguindzberg]

I have the latest openjdk10 and openjdk8 and checked the workaround is not needed.
By merging this PR we are trusting the linked stackoverflow post is right about no version of openjdk ever had the problem.
On the other hand, it makes no harm to execute the workaround on openjdk.
Summary: I am not sure.

[schildbach]

That's good enough, thanks for the testing!