Do not interrupt switch fallthrough

Do not interrupt switch fallthrough

Commit e85c735 introduced the `<check-stats>` function, designated by
`OP_CHECK_STATS`.

This had been inserted below `OP_MAIN_CHANGE_VFOLDER`, which is
`change-vfolder`'s designation; however, `OP_MAIN_CHANGE_VFOLDER` relies
on C's switch fallthrough logic to execute. As a result,
`change-vfolder` executed `check-stats`'s logic instead of the correct
logic.

This commit moves `OP_CHECK_STATS` to above the #ifdef that
`OP_MAIN_CHANGE_VFOLDER` is defined in.