Fix git-subtree metadata for third_party/allwpilib

I renamed it in the past, so this is necessary for further git-subtree
operations to work.

This command fixed it:
 git subtree split --rejoin --prefix=third_party/allwpilib/ HEAD

Split 'third_party/allwpilib/' into commit '00e0908774b67cf417aa07bbcff7da29411e1721'

git-subtree-dir: third_party/allwpilib
git-subtree-mainline: 0dc3e9a89f72d5d7782fb4a07f16becb74a326f6
git-subtree-split: 00e0908774b67cf417aa07bbcff7da29411e1721
Change-Id: I89984fa210cf0246b393e11b0fb23fd1bc99c240