statfs: Fix clang static analyzer error
statfs: Fix clang static analyzer error

If statvfs_local() or stat() returned errors devno[i] was not set,
but later on used. We don't need to continue at all, but we can
simply return an error at this point.

evnu/unionfs-fuse,kissthink/unionfs-fuse-1,kissthink/unionfs-fuse-1,evnu/unionfs-fuse,yogoloth/unionfs-fuse,kissthink/unionfs-fuse-1,yogoloth/unionfs-fuse,yogoloth/unionfs-fuse,evnu/unionfs-fuse