Add windows includes to xmlIO.c

xmlIO.c calls read() and getcwd() which need io.h and direct.h
respectively when compiling on windows. Otherwise, a compiler error may
be raised saying that read() and getcwd() were used implicitly.

This was regressed recently, I'm guessing it was due to the changes to
win32config.h in commit 84085a26

xmlIO.c

@@ -37,6 +37,8 @@
 #if defined(_WIN32)
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
+#include <io.h>
+#include <direct.h>
 #endif
 
 #ifndef S_ISDIR