* New pthread implementation for WinNT/2K/XP. This implementation shouldn't

* New pthread implementation for WinNT/2K/XP. This implementation shouldn't
  be subject to race conditions as it is using SignalObjectAndWait() from the
  Win32 API.
  As this should be somehow slower than the old method (still used on Win9x),
  you can specify that you want to use the old method with the "fast_pthread"
  config option.

* Added a new p_main_sys global variable. This variable is a pointer to an
  OS specific structure which is defined in *_specific.h. This structure can
  be filled by the already existing System_Init() function and is a nice
  way to avoid too many #ifdefs.