In pkg-config <= 0.15.0, the PKG_CHECK_MODULES() autoconf macro would evaluate
its second argument.
In pkg-config 0.16.0, it evaluates it in some places, and quoted in others.
Some Gnome modules such as GTK+ rely on this argument being evaluated, so break
with the new release.
The relevant Gnome bug for this is:
Created attachment 2396 [details] [review]
Here's a patch that makes sure the second argument is evaluated in all
instances, which fixes GTK's configure script.
2005-04-12 Tollef Fog Heen <email@example.com>
* pkg.m4: Patch from James Henstridge to evaluate second argument
again. (Freedesktop #2987, Gnome #300232, Debian #303878,
pkg-config 0.17 released; closing bug
on Jan 18, 2017 at 12:05:39.
(provided by the Example extension).