meta: tell "linguist" that the test resources are vendored
Our test resources shouldn't count toward our language statistics. We
have some PHP checked in to the test resources, but I assure you that we
do not have any production code in PHP and we shouldn't be blamed for
the test data.
gitattributes: let clients use native line endings
Use "text=auto" to ensure that we get LFs in the repository, but
let clients have their native line endings in their worktree.