pkg/54341: x11/gtk3 build fails due to broken glib

[triaxx%netbsd.org@localhost]

>Number:         54341
>Category:       pkg
>Synopsis:       x11/gtk3 build fails due to broken glib
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jul 03 12:00:00 +0000 2019
>Originator:     Frédéric Fauberteau
>Release:        NetBSD 8.0 (pkgsrc-current)
>Organization:
>Environment:
System: etBSD hydralisk.triaxx.org 8.0 NetBSD 8.0 (HYDRALISK) #0: Mon Jan  7 23:57:12 CET 2019  root%hydralisk.triaxx.org@localhost:/mnt/ccd0/netbsd/obj.amd64/sys/arch/amd64/compile/HYDRALISK amd64
Architecture: x86_64
Machine: amd64
>Description:
gtk3 build fails with the following error:
gmake[2]: Entering directory '/mnt/ccd0/pkgsrc/tags/HEAD/x11/gtk3/work/gtk+-3.24.8/gdk'
GLib: Cannot convert message: Conversion from character set â??UTF-8â?? to â??646â?? is not supported
Failed to open file â??./gdk.gresource.xmlâ??: (null)
gmake[2]: *** No rule to make target 'Conversion', needed by 'gdkresources.c'.  Stop.
  GEN      stamp-gdkenumtypes.h
  GEN      gdk.gresource.xml

The complete build.log is available here:
http://pkg.triaxx.org/pub/pkgsrc/logs/devel/gtk3/gtk-3.24.8/build.log
>How-To-Repeat:
cd x11/gtk3 && bmake build
>Fix: