fix InvalidDateFormat error incase of OS LC_TIME setting

[hallkk]

在部分操作系统（ubuntu18.04 LTS Desktop）上，发现因为LC_TIME的原因，导致日志上传失败

code : 400, error msg : {"errorCode":"InvalidRequestTime","errorMessage":"request time 五, 29 3月 2019 03:42:45 GMT not follow RFC822 spec"}

因此在调用strftime方法进行格式化前，设置LC_TIME

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