[lltx] Removed support of dfont format in luaotfload

[Bruno Voisin]

With version 2.7, luaotfload has removed support of dfont format. This is mentioned in NEWS

2016/04/21, luaotfload v2.7:
    [...]
    * Remove support for builtin Fontforge libraries (this includes the PFA,
      PFB, DFONT, and feature file readers).

but no explanation is given for why this was removed. Is this given somewhere?

On OS X the usage of dfont format is rapidly receding and apparently replaced by TTC, but still present for core OS and legacy fonts:

/System/Library/Fonts/Courier.dfont
/System/Library/Fonts/Geneva.dfont
/System/Library/Fonts/Helvetica.dfont
/System/Library/Fonts/HelveticaNeue.dfont
/System/Library/Fonts/Monaco.dfont
/System/Library/Fonts/Times.dfont 

Bruno Voisin