I'm still encountering the same build failure I had reported earlier
today with libxml2, and seem to be having the identical problem with
glib2.  My platform is netbsd-current for i386 from Dec. 20, 2.99.11,
and my pkgsrc has been freshly replaced today (but certainly not all
my packages have been rebuilt).

Doing some digging, it looks like the symptoms of this problem are
identical to those of the problem reported in pkg/28464, but the
resolution to that bug doesn't seem to work in this case.  I'm stymied
on installing xscreensaver and mplayer.  Should I send-pr it?

The error output in both cases includes these lines in config.log:

gcc: couldn't run
`/usr/bin/i386--netbsdelf-gcc--I/usr/pkgsrc/textproc/libxml2/w
ork/.buildlink/include': No such file or directory