!18 jiffs生成程序windows版本改为从华为云镜像下载

Merge pull request !18 from zhOu/master

tools/fsimage/win-x86/flash_eraseall

-#!/bin/sh
-echo "${0##*/} has been replaced by \`flash_erase <mtddev> 0 0\`; please use it" 1>&2
-[ $# -ne 0 ] && set -- "$@" 0 0
-exec flash_erase "$@"