修复tprofiler.log无法输出数据，只有=号的问题

[DevenWen]

如题，MysqlProfFilter和ProfFilter有不合理的地方，导致bug，我在Issues上说明了一下，现在向项目提交一个pull request关于tprofiler.log无法产生日志，只有=号的问题

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