[werror] Fix mismatched tags (struct vs. class) inconsistence

Signed-off-by: Thorsten Behrens <tbehrens@suse.com>
I think that lack of typechecking is par for the course for C APIs?  Maybe there is a better way than typedef to void *, but whatever it is, we really shouldn't be exposing the internal CamelCaps typename here... which is why Christophe ran into the struct vs class warning previously.