Our git version is v2+ for some time now, but go.mod
still declared v1. Hopefully making both match makes
https://pkg.go.dev/github.com/rfjakob/gocryptfs/v2 work.
All the import paths have been fixed like this:
find . -name \*.go | xargs sed -i s%github.com/rfjakob/gocryptfs/%github.com/rfjakob/gocryptfs/v2/%
xfstests generic/523 discovered that we allowed to set
xattrs with "/" in the name, but did not allow to read
them later.
With this change we do not allow to set them in the first
place.
