Log Message:
fontconfig: remove libuuid bl3 inclusion in buildlink3.mk

libuuid is marked as a private dependency and it is an implementation
detail.

On some platforms (e.g. NetBSD) by including libuuid bl3 fonts/fontconfig was
unconditionally installed due that.

Problem originally analyzed by <wiz> in:

 <https://mail-index.NetBSD.org/tech-pkg/2019/06/19/msg021438.html>

And change proposed on tech-pkg@:

 <https://mail-index.NetBSD.org/tech-pkg/2020/07/13/msg023550.html>

Thanks to <wiz> also for reviews, suggestions and discussions!