修复clock_gettime返回类型错误，修复小时间间隔duration返回0问题

[xiaolin2004]

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[fslongjin]

#623

[fslongjin]

这个值不正确，在shell里面输入date命令，看到的时间完全不对（间隔1秒输入date，但是时间增长了几十秒）。