* INSTALL.win32, include/vlc_config.h, src/libvlc.h: changes to reflect the
   fact that libdvdcss now needs a colon after the DVD drive letter (on Win32).

* src/misc/messages.c: on Win32 only use fflush() if in debug mode.

* src/misc/win32_specific.c: try to raise the our process priority slightly
   above normal. This prevent us from suffering too much from normal activity
   of the OS.