Makefile

This corrects the linker flag from `--static` to `-static` (single dash).

It also creates the `obj` directory that is needed to store the object files, and by default is missing and thus `make` fails. 
`obj` is also tagged as a phony target in order to fail early if a file named 'obj' already exists.

I would personally prefer getting rid of the `obj` directory and have the object files side by side the source files. `clean` isn't any easier with an `obj` directory really, as it can just be `rm -f ${OBJ_FILES} stutsk`. Creating in new paths always adds some trouble - you are modifying/extending an existing hierarchy when you cannot guarantee that the environment will be clean (e.g. that an `obj` file is not already there and if it's needed). 

`stutsk` looks fun :) (other than the fact that I cannot pronounce it).
What does it mean ?  `st`ack(?)`utsk`(!?)