[Fontconfig] Make GTK+ apps (and Gnome) fully respect your .fonts.conf

[Erik]

Well, specifically, what I had in my .fonts.conf was a default setting 
of BCI full hinting for all fonts.  After that, I had configuration to 
use slight hinting for specific fonts.  I found that Gnome (Cairo) apps 
would not respect this, for whatever reason, whereas KDE (Qt) would.  
Gnome apps would just do brute-force full-hinting of everything.  This 
patch on cairo fixed the issue and things then rendered as they do in 
KDE.  I actually was using MOZ_DISABLE_PANGO=1 before starting firefox, 
and now I no longer have to with the patched cairo. 

Perhaps I have a unique configuration in my .fonts.conf that exposed 
this.  All I know is that it works now.