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_pth.h b/Python/thread_pth.h
index 6596b1a..71e0d04 100644
--- a/Python/thread_pth.h
+++ b/Python/thread_pth.h
@@ -44,7 +44,7 @@
  */
 
 
-int PyThread_start_new_thread(void (*func)(void *), void *arg)
+long PyThread_start_new_thread(void (*func)(void *), void *arg)
 {
 	pth_t th;
 	dprintf(("PyThread_start_new_thread called\n"));
@@ -56,7 +56,7 @@
 				 (void *)arg
 				 );
 
-	return th == NULL ? 0 : 1;
+	return th;
 }
 
 long PyThread_get_thread_ident(void)