Klib .api file does not use tabs

[JakeWharton]

The JVM-based .api files use tabs. Tabs are objectively the best mechanism of indent 😀 . Can we use tabs in the klib files, too?

[fzhinkin]

It's a way to preserve diversity across various indentation mechanisms. :)

Jokes aside, spaces are emitted by the compiler's library, so it's not that easy to swap it to tabs.
If there is no other reason to use tabs beside lower disk footprint and personal preferences, I'd prefer leaving it as it is now.