while not running the whole VLC as root - closes #440

* unify the Time-To-Live string and fix its Spanish translation (thanks to the forum user martintxo)

* fixed the compilation of libmpcdec, so INSTALL_NAME runs finely. Please check whether this script should run on win32/linux/BeOS as well.

- Some cleanup

Minor headers cleanup

  - It should also no longer crash if you select macosx as an extraintf. This is not allowed. It is the cause of the NSDictionary crash reported often in the forums. Notice however that if you have selected a primary interface that is not macosx, you might end up with a "blank application" forcing you to reset the preferences manually (your fault for mocking with them in the first place).
  - Should fix clivlc mode. (this mode allows you to run VLC on OSX while no user is logged in, in the GUI).

Thanks to Jean-Michel Vallat for kicking my ass. :D

* Free scandir results when we are done with them. Issue pointed out by jmvallat_vlc at mac dot com.