Previously:

    (unknown(inode=1)) error: function not implemented

Now:

    (*bazilfuse.GetxattrRequest(inode=1)) error: function not implemented

For GoogleCloudPlatform/gcsfuse#76.

This wasn't useful to users to begin with, and an API change in bazil.org/fuse
made it non-functional.

Fixes #10.

For #10.

Fixes #9.

This manifested as ForgetFSTest.MkDir pacicking now and then in a manner
like this:

    https://gist.githubusercontent.com/jacobsa/2d12150beca1043f71b0/raw/28e0a01a9276799ad820970a05b522367222c331/gistfile1.txt

For #9.