bug#30553: 26.0.91; underline appears beneath line-spacing rather than beneath text

[Eli Zaretskii]

> Date: Mon, 26 Feb 2018 22:41:33 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: alptekin.aker@gmail.com, 30553@debbugs.gnu.org
> 
> IMO, it's better to make x-underline-at-descent-line a tristate
> variable than add another boolean.

Btw, there's also underline-minimum-offset.  Did you try playing with
it?