Fix build issue on OSX 10.4
diff --git a/Mac/Modules/MacOS.c b/Mac/Modules/MacOS.c
index 99e531b..9148fe0 100644
--- a/Mac/Modules/MacOS.c
+++ b/Mac/Modules/MacOS.c
@@ -30,6 +30,9 @@
 #include <Carbon/Carbon.h>
 #include <ApplicationServices/ApplicationServices.h>
 
+#ifndef HAVE_MACOS105_SDK
+typedef SInt16	FSIORefNum;
+#endif
 
 static PyObject *MacOS_Error; /* Exception MacOS.Error */