build_os2emx.patch in issue 3868 - update OS/2 EMX makefile and config files

Part of source_os2emx.patch in issue 3868:
  Include/pystrcmp.h:  OS/2 has same C APIs as Windows
  Lib/test/test_io.py: OS/2 has same behaviour as Windows for this test

Reviewed by Amaury Forgeot d'Arc
diff --git a/Include/pystrcmp.h b/Include/pystrcmp.h
index edb1239..369c7e7 100644
--- a/Include/pystrcmp.h
+++ b/Include/pystrcmp.h
@@ -8,7 +8,7 @@
 PyAPI_FUNC(int) PyOS_mystrnicmp(const char *, const char *, Py_ssize_t);
 PyAPI_FUNC(int) PyOS_mystricmp(const char *, const char *);
 
-#ifdef MS_WINDOWS
+#if defined(MS_WINDOWS) || defined(PYOS_OS2)
 #define PyOS_strnicmp strnicmp
 #define PyOS_stricmp stricmp
 #else