bug#15420: 24.3; Symbols like 🚴 (U+1F6B4) are not displayed by default

[Eli Zaretskii]

> From: Stephen Berman <stephen.berman@gmx.net>
> Date: Thu, 15 Aug 2019 11:01:04 +0200
> Cc: Mike FABIAN <maiku.fabian@gmail.com>, 15420@debbugs.gnu.org
> 
> I have both the Symbola and Aegyptus fonts installed; when I run emacs
> with -Q, only the bicycle and bicyclist characters are correctly
> displayed, the Egyptian hieroglyph is displayed as a hex box.  But when
> I then set the default font (e.g. via the Options menu) to Aegyptus
> Regular, all three characters are correctly displayed.  So the installed
> Symbola fonts are found by default, but not the installed Aegyptus
> fonts.

It probably means that Aegyptus doesn't announce any features we are
looking for when searching for a suitable font.  Or maybe the Egyptian
Hieroglyphs lack something in our data structures used for font
lookup (see fontset.el).