To make it usable with stock version of `erlang.mk`.
I'm trying to use `cf` from withing erlang.mk-based project, but it
fails to properly autopatch it. erlang.mk magic works properly when
Makefile contains some references to `rebar`.
Proper fix will be available within
https://github.com/ninenines/erlang.mk/issues/586
But currently it's far more easier to add single target to this project,
than to delve into shell script/make spaghetti =)
