Make hieroglyphs display correctly with existing fonts

* etc/HELLO: Remove hieroglyph format control characters.

* lisp/language/misc-lang.el: Add a rule to compose Egyptian
hieroglyphs even without Unicode format control characters.

etc/HELLO

@@ -38,7 +38,7 @@ Czech (čeština)	Dobrý den
 Danish (dansk)	Hej / Goddag / Halløj
 Dutch (Nederlands)	Hallo / Dag
 Efik  /ˈɛfɪk/	Mɔkɔm
-Egyptian Hieroglyphs (𓂋𓐰𓏤𓈖𓆎𓅓𓏏𓐰𓊖)	𓅓𓊵𓐰𓐷𓏏𓊪𓐸, 𓇍𓇋𓂻𓍘𓇋
+Egyptian Hieroglyphs (𓂋𓏤𓈖𓆎𓅓‌𓏏𓊖)	𓅓𓊵𓏏𓊪, 𓇍𓇋𓂻𓍘𓇋
 Emacs	emacs --no-splash -f view-hello-file
 Emoji	👋
 English /ˈɪŋɡlɪʃ/	Hello

lisp/language/misc-lang.el

@@ -192,7 +192,20 @@ thin (i.e. 1-dot width) space."
    composition-function-table
    #x13437
    (list (vector "\U00013437[\U00013000-\U0001343F]+"
-                 0 #'egyptian-shape-grouping))))
+                 0 #'egyptian-shape-grouping)))
+  ;; As of late 2021, Egyptian Hieroglyph Format Controls are not yet
+  ;; supported in existing fonts and shaping engines, but some fonts
+  ;; do provide ligatures with which texts in Egyptian Hieroglyphs are
+  ;; correctly displayed.  If and when these format controls are
+  ;; supported, the five lines below (which cancel the effect of the
+  ;; above lines) can be removed, and the entry in etc/HELLO can be
+  ;; restored to:
+  ;; Egyptian Hieroglyphs (𓂋𓐰𓏤𓈖𓆎𓅓𓏏𓐰𓊖)	𓅓𓊵𓐰𓐷𓏏𓊪𓐸, 𓇍𓇋𓂻𓍘𓇋
+  (set-char-table-range
+   composition-function-table
+   '(#x13000 . #x1342E)
+   (list (vector "[\U00013000-\U0001342E]+"
+                 0 #'font-shape-gstring))))
 
 (provide 'misc-lang)