Update use of errno for newer Windows CE versions.

zutil.c

@@ -136,8 +136,8 @@ const char * ZEXPORT zError(err)
     return ERR_MSG(err);
 }
-#if defined(_WIN32_WCE)
-    /* The Microsoft C Run-Time Library for Windows CE doesn't have
+#if defined(_WIN32_WCE) && _WIN32_WCE < 0x800
+    /* The older Microsoft C Run-Time Library for Windows CE doesn't have
      * errno.  We define it as a global variable to simplify porting.
      * Its value is always 0 and should not be used.
      */