Re-apply userStatData fix
Re-apply userStatData fix

Fix[0] lost in refactoring[1].

[0]: https://github.com/prometheus/mysqld_exporter/commit/dbad3dcf71d5eb6a659aaacf4fb86253b9da15a5
[1]: https://github.com/prometheus/mysqld_exporter/commit/58de609465439a1074306db1299cad7dcec0c23c#diff-7f3e92469561ad831b3efc026d4ffcddR875

roman-vynar/mysqld_exporter,roman-vynar/mysqld_exporter,rtreffer/mysqld_exporter,growbots/mysqld_exporter,prometheus/mysqld_exporter,prometheus/mysqld_exporter