SF patch 473749 compile under OS/2 VA C++, from Michael Muller.
Changes enabling Python to compile under OS/2 Visual Age C++.
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 5f5ae4c..b6e4460 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -567,7 +567,11 @@
 #ifndef RISCOS
 	if (!stat(filename, &s)) {
 		if (S_ISDIR(s.st_mode))
+#if defined(PYOS_OS2) && defined(PYCC_VACPP)
+			errno = EOS2ERR;
+#else
 			errno = EISDIR;
+#endif
 		else
 			exists = 1;
 	}