gentoo/qt — pull request #70 by mrueg (2014-08-17 21:35:05+00:00)
Title: [qt5-build.eclass] Use usex operator.

Maybe you want to give usex operator a try here?

"USAGE: usex 〈USE flag〉 [true output] [false output] [true suffix] [false suffix]
DESCRIPTION:
If USE flag is set, echo [true output][true suffix] (defaults to "yes"),
otherwise echo [false output][false suffix] (defaults to "no")."