RFR: Add tabfiles to jcheck configuration [v4]

[Erik Helin]

On Wed, 11 Nov 2020 17:55:25 GMT, Magnus Ihse Bursie <ihse at openjdk.org> wrote:

>> The tabfiles setting is just like the files setting, but it lists files in which tabs are allowed.
>> 
>> (This is to support makefiles)
>
> Magnus Ihse Bursie has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Add tests of ignore-tabs jcheck functionality.

Looks good!

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Marked as reviewed by ehelin (Reviewer).

PR: https://git.openjdk.java.net/skara/pull/929