Sjoerd's thread changes (including down_sema typo fix).
Note: waitflag not supported on NT.
diff --git a/Python/thread_os2.h b/Python/thread_os2.h
index f9eda92..00a5244 100644
--- a/Python/thread_os2.h
+++ b/Python/thread_os2.h
@@ -203,9 +203,9 @@
 
 }
 
-void down_sema(type_sema aSemaphore)
+void down_sema(type_sema aSemaphore, int waitflag)
 {
-
+  return -1;
 }
 
 void up_sema(type_sema aSemaphore)