s3: Fix a pointer error

s3: Fix a pointer error

It is not universally guaranteed that an enum is represented as a uint32_t.

This starts to be THE BUG (tm) in Samba. What can I do to explain this
to people a bit better? It seems that the verbose explanations I put into
the recent checkins fixing similar bugs are not clear enough.

Anybody who does is not 100% clear about what this patch fixes please
contact me directly so that we can talk it through on the phone to agree
on a wording that everybody can understand.

Thanks,

Volker