Adapt tramp to new autoload-macro expand

Bug #78995.

* lisp/net/tramp-compat.el (tramp-loaddefs): suppress error on requiring
tramp-loaddef.
* lisp/net/tramp.el (tramp--with-startup): declare autoload-macro
expand, and suppress warnings about this declare form on older versions
of Emacs.

lisp/net/tramp-compat.el

@@ -29,7 +29,7 @@
 
 ;;; Code:
 
-(require 'tramp-loaddefs)
+(require 'tramp-loaddefs nil t)  ; guard against load during autoload gen
 (require 'ansi-color)
 (require 'auth-source)
 (require 'format-spec)

lisp/net/tramp.el

@@ -103,8 +103,15 @@
 
   (put 'tramp--startup-hook 'tramp-suppress-trace t)
 
+  ;; TODO: once (autoload-macro expand) is available in all supported
+  ;; Emacs versions, this can be eliminated:
+  ;;  backward compatibility for autoload-macro declare form
+  (unless (assq 'autoload-macro macro-declarations-alist)
+    (push '(autoload-macro ignore) macro-declarations-alist))
+
   (defmacro tramp--with-startup (&rest body)
     "Schedule BODY to be executed at the end of tramp.el."
+    (declare (autoload-macro expand))
     `(add-hook 'tramp--startup-hook (lambda () ,@body)))
 
   (eval-and-compile