glog 错误控制

log_level: INFO(0), WARNING(1), ERROR(2), FATAL(3),

输出到那？ Set to GLOG_logtostderr=1 in command to output log to stderr, default is 0 will be output to logfile
输出何种级别：FLAGS_minloglevel = xx; level bigger than xx will outpu (to logfile or stderr),

当日志设置为输出到文件时（GLOG_logtostderr=0）何时输出到终端stderr? google::SetStderrLogging(xx); level bigger than xx will outpu to stderr,