Add _P_WAIT etc. for NT.

Modules/posixmodule.c

@@ -1461,6 +1461,8 @@ posix_spawnv(self, args)
 	}
 	argvlist[argc] = NULL;
 
+	if (mode == _OLD_P_OVERLAY)
+		mode = _P_OVERLAY;
 	i = _spawnv(mode, path, argvlist);
 
 	PyMem_DEL(argvlist);
@@ -1567,6 +1569,8 @@ posix_spawnve(self, args)
 	}
 	envlist[envc] = 0;
 
+	if (mode == _OLD_P_OVERLAY)
+		mode = _P_OVERLAY;
 	i = _spawnve(mode, path, argvlist, envlist);
 	if (i == -1)
 		(void) posix_error();
@@ -3431,6 +3435,14 @@ all_ins(d)
         if (ins(d, "O_TEXT", (long)O_TEXT)) return -1;
 #endif
 
+#ifdef HAVE_SPAWNV
+        if (ins(d, "_P_WAIT", (long)_P_WAIT)) return -1;
+        if (ins(d, "_P_NOWAIT", (long)_P_NOWAIT)) return -1;
+        if (ins(d, "_P_OVERLAY", (long)_OLD_P_OVERLAY)) return -1;
+        if (ins(d, "_P_NOWAITO", (long)_P_NOWAITO)) return -1;
+        if (ins(d, "_P_DETACH", (long)_P_DETACH)) return -1;
+#endif
+
 #if defined(PYOS_OS2)
         if (insertvalues(d)) return -1;
 #endif