MacPython-OS9 has its own copy of the interrupt handling code. Added PyErr_SetInterrupt() here too.
diff --git a/Mac/Python/macglue.c b/Mac/Python/macglue.c
index 51d73ed..3711610 100644
--- a/Mac/Python/macglue.c
+++ b/Mac/Python/macglue.c
@@ -283,6 +283,12 @@
 #endif /* USE_STACKCHECK */
 
 #if !TARGET_API_MAC_OSX
+void
+PyErr_SetInterrupt(void)
+{
+	interrupted = 1;
+}
+
 /* The catcher routine (which may not be used for all compilers) */
 static RETSIGTYPE
 intcatcher(sig)