Fix autotester whitespace failure

[RazvanN7]

Replaced tabs with whitespaces.

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[thewilsonator]

Thanks!

[WalterBright]

Why didn't the checkwhitespace program say which file it was?

[RazvanN7]

It's probably a bug in the autotester stdin/stderr redirect. Running the command locally gives all the information, including the file and line.