Win32 changes only:

 - defined off_t as a long long. This allows DVD navigation to work.
   This change is to be implemented on a compiler by compiler basis. For
   now, it works on mingw32 (tested) and should work on MSVC (not tested).

 - Implemented a quick and dirty hack in intf_msg.c to be able to display
   long long integers with printf on Win32. This change is also necessary
   to avoid segfaults when debug is enabled in vlc on Win32.

 - few minor changes in the directx plugins.

 - defined snprintf in common.h and removed a few #ifdef WIN32