Can't export PFS or null mount to Linux

[Matthew Dillon]

    I had some time and tracked this one down.  It should be possible to
    export PFS's via NFS to linux now.

    The bug was in the readdirplus rpc, which linux uses by default.  Well,
    not really a bug, the NFS code simply did not supply enough information
    to HAMMER for HAMMER to be able to determine which PFS to lookup the
    inode number in.

    --

    I also noticed that the d_ino field for directory entries returned
    by NFS was being truncated to 32 bits, and fixed that as well.

						-Matt