Restore support for Microsoft VC6 compiler.
Some functions in the msvcrt module are skipped,
and socket.ioctl is enabled only when using a more recent Platform SDK.

(and yes, there are still companies that use a 10-years old compiler)
diff --git a/Modules/errnomodule.c b/Modules/errnomodule.c
index 696d396..642d721 100644
--- a/Modules/errnomodule.c
+++ b/Modules/errnomodule.c
@@ -5,7 +5,7 @@
 
 /* Windows socket errors (WSA*)  */
 #ifdef MS_WINDOWS
-#include <winsock.h>
+#include <windows.h>
 #endif
 
 /*