I've been waiting 8 years for KSR to re-emerge from bankruptcy.  If they
ever do, they can damn well #define _POSIX_THREADS their own damn selves.
diff --git a/Python/thread.c b/Python/thread.c
index 1979df0..b35a48b 100644
--- a/Python/thread.c
+++ b/Python/thread.c
@@ -36,10 +36,6 @@
 
 #include "pythread.h"
 
-#ifdef __ksr__
-#define _POSIX_THREADS
-#endif
-
 #ifndef _POSIX_THREADS
 
 #ifdef __sgi