Windows patch: _dbus_printf_length

[Peter Kümmel]

I forgot the diff for dbus/dbus-sysdeps.c:

+#ifndef DBUS_WIN
+/**
+ * Measure the message length without terminating nul
+ */
+int _dbus_printf_length (const char *format,
+                         va_list args)
+
+{
+  char c;
+  return vsnprintf (&c, 1, format, args);
+}
+#endif
+

Ralf, do you think this will work with mingw?
Then we should check for gcc instead for windows.

Peter