Port contrib/netbsd-tests/fs/tmpfs/h_tools.c to FreeBSD

• Add inttypes.h #include for PRId64 macro
• Use FreeBSD's copy of getfh(2), which doesn't include a fh_size parameter. Use sizeof(fhandle_t) instead as the size of fhp is always fixed as fhandle_t, unlike NetBSD's copy of fhp, which is void*.

MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division