* Change win32 client Sys_Sleep so it ONLY sleeps since before it was waking on

more or less any input event; fine for the server, not so much use for the
  client
* In the main loop, don't bother sleeping if it's going to be less than 10ms as
  the methods we're using to sleep at the moment aren't very precise
* Add Sys_PlatformInit for platform specific initialisation
* In win32 Sys_PlatformInit force selection of the DirectX SDL backend in order
  to get better fullscreen mouse input (in conjunction with a patched SDL DLL
  http://bugzilla.libsdl.org/show_bug.cgi?id=265)

code/sys/sys_unix.c

@@ -511,3 +511,15 @@ void Sys_ErrorDialog( const char *error )
 
 	FS_FCloseFile( f );
 }
+
+/*
+==============
+Sys_PlatformInit
+
+Unix specific initialisation
+==============
+*/
+void Sys_PlatformInit( void )
+{
+	// NOP
+}