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/importdl.h b/Python/importdl.h
index 4193620..76fd05d 100644
--- a/Python/importdl.h
+++ b/Python/importdl.h
@@ -38,6 +38,7 @@
 typedef FARPROC dl_funcptr;
 #else
 #ifdef PYOS_OS2
+#include <os2def.h>
 typedef int (* APIENTRY dl_funcptr)();
 #else
 typedef void (*dl_funcptr)(void);