bug#51402: 29.0.50; build error

[Enoch H Wexler]

d8caa3d9fb * master origin/master

make -C ../admin/grammars all EMACS="../../src/bootstrap-emacs"
make[3]: Entering directory '/home/enoch/emacs/admin/grammars'
make[3]: Nothing to be done for 'all'.
make[3]: Leaving directory '/home/enoch/emacs/admin/grammars'
  GEN      calendar/diary-loaddefs.el
Source file ‘/home/enoch/emacs/lisp/help-mode.el’ newer than byte-compiled file; using older file
Debugger entered--Lisp error: (error "Autoloading file /home/enoch/emacs/lisp/help-mode....")
  help-mode--add-function-link(#("C-x s" 0 5 (font-lock-face help-key-binding face help-key-binding)) save-some-buffers)
  substitute-command-keys("Memory exhausted--use \\[save-some-buffers] then ex...")
  command-line()
  normal-top-level()

make[2]: *** [Makefile:478: calendar/diary-loaddefs.el] Error 255
make[2]: Leaving directory '/home/enoch/emacs/lisp'
make[1]: *** [Makefile:835: ../lisp/loaddefs.el] Error 2
make[1]: Leaving directory '/home/enoch/emacs/src'
make: *** [Makefile:450: src] Error 2