shouldLengthIncludeIndent only works for space indentation

[wleoncio]

When using tabs for indentation, setting "comment-divider.shouldLengthIncludeIndent": false doesn't properly respect the length defined by comment-divider.length. In my tests, the overflow varies from 1 extra character (when tab =< 4 spaces) to 3 extra characters (when tab = 4 spaces).