FreeBSD port

[dverite]

• deal with lack of dirent.d_off on FreeBSD
• make xattr* functions essentially no-ops
• skip prctl() and setrlimit()
• some differences in struct statfs
• some mount options lacking
• replace SOL_TCP by IPPROTO_TCP
• use linux value for errno EOPNOTSUPP

[garlick]

Thanks for submitting this. What results do you get from make check on freebsd?

The os ifdefs should probably be converted to autoconf feature tests, however as that's tedious work and this projects build system needs a cleanup pass anyway we can probably defer that.

Is there a specific use case you are supporting here?

I'm about to check this out on my FreeNAS box but have to get a few things tweaked there first.

[garlick]

Never mind on the make check question - I see the tests need to be made tolerant of missing bits before we'll get anywhere with that. Still interested in your use case though.

[dverite]

Some specific autoconf checks would be a nice addition, notably for setfsuid/gid and xattrs.
Currently autoreconf fails for me on FreeBSD, I've built from a pre-autoconf'ed+make dist archive on Linux.
Use case: the user is a hosting service that has lots of ZFS volumes on FreeBSD: diod/9p is considered as an alternative to NFS (linux client/server on FreeBSD), and also to native ZFS on Linux.

[garlick]

I'll go ahead and merge this and we can follow up with the cleanup later.