pkg/53690: x11/gtk3 build fails on NetBSD 7.2

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         53690
>Category:       pkg
>Synopsis:       x11/gtk3 build fails on NetBSD 7.2
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Oct 29 13:10:00 +0000 2018
>Originator:     Andreas Gustafsson
>Release:        NetBSD 7.2
>Organization:

>Environment:
System: NetBSD
Architecture: x86_64
Machine: amd64
>Description:

Building x11/gtk3 (gtk+-3.24.1) on NetBSD 7.2 fails with:

  gtkfontchooserwidget.c:61:31: fatal error: freetype/freetype.h: No such file or directory
   #include <freetype/freetype.h>
                                 ^

This happens even on a freshly installed 7.2 system with no
pre-existing packages.

>How-To-Repeat:

>Fix: