bug#22927: system-installed emacs does not find system-installed fonts

[myglc2]

Not technically not a bug because the doc says ...

2.6.2 X11 Fonts

The ‘fontconfig’ package in Guix looks for fonts in
‘$HOME/.guix-profile’ by default.  Thus, to allow graphical applications
installed with Guix to display fonts, you have to install fonts with
Guix as well.

But it does seem counter-intuitive that emacs 'M-x list-fontsets' gives ...

Fontset: -*-*-*-*-*-*-*-*-*-*-*-*-fontset-default
Fontset: -*-fixed-medium-r-normal-*-16-*-*-*-*-*-fontset-standard
Fontset: -urw-Nimbus Mono L-normal-normal-normal-*-13-*-*-*-m-0-fontset-startup

... when the system package list is ...

  % *Guix Package L...      5437 Guix-Output-List
  
  [...]
  emacs                24.5       out       Yes          The extensible, 
customizable, self-documenting text editor
  [...]
  font-dejavu          2.34       out       Yes          Vera font  family 
derivate with additional characters
  [...]