[fprint] libfprint portability fixes

[Daniel Drake]

joshua stein wrote:
> these patches allow libfprint to compile on openbsd 4.2-current
> where i have it working properly with the authentec aes2501 device
> on my fujitsu lifebook p1610.

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.

> patch-configure: -Wextra isn't supported by our gcc, -Wshadow breaks

I find these flags useful, so they should either be made Linux-only or 
detected/tested (at configure time). The correct file to modify in that 
case is configure.ac and needs some autoconf magic to do this

> patch-libfprint_Makefile_in: -fvisibility=hidden not supported

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?

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

> patch-libfprint_fp_internal_h: ENOTSUP, ENODATA, and EPROTO are not
> defined on openbsd

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.

Thanks,
Daniel