mknod: Consider zero type as S_IFREG
E.g. Linux kernel considers zero type passed to mknod(at) as S_IFREG (regular file), and e.g. tar relies on it for extended attribute support at least up to the current version (tar 1.35).
Fix fakeroot to create a regular file to match Linux behaviod instead of creating a "typeless" file.
Without this commit the affected tar versions may enter an infinite retry loop when creating a file with xattrs.