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/Lib/test/test_io.py b/Lib/test/test_io.py
index 7fad7c7..9ef2a81 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -201,7 +201,7 @@
         # On Windows and Mac OSX this test comsumes large resources; It takes
         # a long time to build the >2GB file and takes >2GB of disk space
         # therefore the resource must be enabled to run this test.
-        if sys.platform[:3] == 'win' or sys.platform == 'darwin':
+        if sys.platform[:3] in ('win', 'os2') or sys.platform == 'darwin':
             if not test_support.is_resource_enabled("largefile"):
                 print("\nTesting large file ops skipped on %s." % sys.platform,
                       file=sys.stderr)