arch/um/Makefile passes the -f option to the ln command:

  linux: vmlinux
          @echo '  LINK $@'
          $(Q)ln -f $< $@

So, the hard link is always re-created, and the old one is removed
anyway.
Signed-off-by: NMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: NKees Cook <keescook@chromium.org>