[fprint] libfprint portability fixes

[joshua stein]

> Thanks for your effort. I realise that these aren't necessarily intended as "proper" 
> fixes, but I've put some comments below. I've put these items on my TODO list but I'll 
> happily accept any patches that fix this properly.

right, these are just what will be provided with the openbsd
port/package.

> Same comments as for the -Wextra/-Wshadow flags.
> Also, even with your patch applied does it not choke on the API_EXPORTED define used in 
> many function declarations?

it does not.  i can send you a full build log off-list if you're
interested.

> And just for curiosity, which gcc version is OpenBSD shipping currently?

3.3.5

> Can you point me to a list of error codes on OpenBSD (and their numeric values)? This 
> part looks fine, although I'll probably switch to EOPNOTSUPP everywhere rather than 
> using ENOTSUP.

http://www.openbsd.org/cgi-bin/cvsweb.cgi/src/sys/sys/errno.h?rev=1.20&content-type=text/x-cvsweb-markup