[luatex] tounicode problem when gsub feature applied

[Arthur Reutenauer]

> the resulting code is completely weird and beyond BMP:
> F0096 F0333 F0551 F0084 F0308 F0555

  This is perfectly reasonable, it's the in private use area.  I suppose
those are the character codes actually used in the font.

  Of course, it still means we need a ToUnicode CMap.

	Arthur