Partial patch from SF #452266, by Jason Petrone.

This changes Pythread_start_thread() to return the thread ID, or -1
for an error.  (It's technically an incompatible API change, but I
doubt anyone calls it.)
diff --git a/Python/thread_cthread.h b/Python/thread_cthread.h
index 0805051..8487cc2 100644
--- a/Python/thread_cthread.h
+++ b/Python/thread_cthread.h
@@ -14,7 +14,7 @@
 /*
  * Thread support.
  */
-int
+long
 PyThread_start_new_thread(void (*func)(void *), void *arg)
 {
 	int success = 0;	/* init not needed when SOLARIS_THREADS and */
@@ -27,7 +27,7 @@
 	 * so well do it here
 	 */
 	cthread_detach(cthread_fork((cthread_fn_t) func, arg));
-	return success < 0 ? 0 : 1;
+	return success < 0 ? -1 : 0;
 }
 
 long