mozilla/rust — pull request #9565 by Heather (2013-09-27 10:54:44+00:00)
Title: support for GNU configure syntax

It will be useful for unix systems, some package managers and external tools that is passing / maybe looking for GNU configure syntax options.

One of related bugs: https://github.com/mozilla/rust/issues/5138

Also that could be useful in future if project will really install man pages / other stuff using those variables.