Allow use of \N{...} earlier to help fix bug#79353

* lisp/emacs-lisp/shorthands.el (hack-read-symbol-shorthands):
Avoid inf-loops during bootstrap.
E.g. this can occur while loading `uni-special-lowercase.el` where
`hack-local-variables--find-variables` uses `downcase` which triggers
loading `uni-special-lowercase.el`, ...

* lisp/international/mule-cmds.el (ucs-names): Explicitly require
`charprop`.

* src/Makefile.in ($(lispsource)/loaddefs.el): Depend on `charprop`.

lisp/emacs-lisp/shorthands.el

@@ -36,7 +36,11 @@
   ;; detail of files.el.  That function should be exported,
   ;; possibly be refactored into two parts, since we're only
   ;; interested in basic "Local Variables" parsing.
-  (alist-get 'read-symbol-shorthands (hack-local-variables--find-variables)))
+  ;; FIXME: Disable ourselves temporarily to avoid inf-loops during bootstrap,
+  ;; trying to look for shorthands in the files that implement shorthands.
+  (let ((hack-read-symbol-shorthands-function #'ignore))
+    (alist-get 'read-symbol-shorthands
+               (hack-local-variables--find-variables))))
 
 (setq hack-read-symbol-shorthands-function #'hack-read-symbol-shorthands)
 

lisp/international/mule-cmds.el

@@ -3125,6 +3125,7 @@ on encoding."
 	       (#xE0000 . #xE01FF)))
             (gc-cons-threshold (max gc-cons-threshold 10000000))
 	    (names (make-hash-table :size 42943 :test #'equal)))
+	(require 'charprop) ;; Usually preloaded, but not during bootstrap.
         (dolist (range ranges)
           (let ((c (car range))
 	        (end (cdr range)))

src/Makefile.in

@@ -948,7 +948,9 @@ NATIVE_COMPILATION_AOT = @NATIVE_COMPILATION_AOT@
 endif
 
 ifneq ($(XCONFIGURE),android)
-$(lispsource)/loaddefs.el: | bootstrap-emacs$(EXEEXT) $(bootstrap_pdmp)
+$(lispsource)/loaddefs.el: |  		       \
+    bootstrap-emacs$(EXEEXT) $(bootstrap_pdmp) \
+    $(lispsource)/international/charprop.el
 	$(MAKE) -C ../lisp autoloads EMACS="$(bootstrap_exe)"
 endif