[gssproxy] Git history rewrite

[Robbie Harwood]

As part of fixing [182] (Match repository heirarchy and dist tarball
heirarchy), we will be force-pushing an edited commit tree.  Three
change have been made:

- The "proxy" subdir has been eliminated and all its contents exist at
  the root.  This addresses the immediate issue.

- rpcgen/README has accordingly been updated to reflect the new correct
  path to the .x files.

- Makefile.am had an include removed that would now point outside the
  tree.

No further changes have been made.

We apologize for the inconvenience this will cause.  You should be able
to adapt your existing branches like so:

    git checkout work_branch
    git format-patch master..
    mv *.patch /tmp
    git checkout master
    git fetch upstream
    git reset --hard upstream/master
    git checkout work_branch
    git reset --hard master
    git am -p2 /tmp/*.patch

Thanks,
--Robbie

182: https://pagure.io/gssproxy/issue/182