[Mingw-cross-env-list] "Nothing to be done" message when trying to rebuild

[Nikos Chantziaras]

I made an *.mk file for libmodplug (to use it as the MOD backend of 
SDL_mixer.)  It builds and installs fine the first time.  But if I try 
to build it again, I get:

  $ make libmodplug
  make: Nothing to be done for `libmodplug'

The only way to get it to build again is to delete 
./usr/installed/libmodplug.  Why is that?

Here's the mk file: http://pastebin.com/raw.php?i=adGdjmqD