bug#48143: 28.0.50; emacs-26.1-147099-gab7a61e0ef fails to build (update/fix)

[Horst von Brand]

I grabbed the latest git version, did a `make clean`. The configuration is as 
stated below for this (older) version. Then `make` fails:
```
make[2]: Entering directory '/home/vonbrand/tmp/emacs/lisp'
  ELC      textmodes/makeinfo.elc

In toplevel form:
textmodes/makeinfo.el:71:1: Error: Cannot open load file: No such file or 
directory, texinfo-loaddefs
make[2]: *** [Makefile:301: textmodes/makeinfo.elc] Error 1
```

Reverting 68bf917896daa10601c3fdff172205e9aa06d155 ("Automatically generate 
texinfo.el internal autoloads") fixes the build.

In GNU Emacs 28.0.50 (build 149, x86_64-pc-linux-gnu, GTK+ Version 3.24.29, 
cairo version 1.17.4)
 of 2021-04-27 built on localhost.localdomain
Repository revision: d55d5358b27dee15ebbd998131d22b221f5f4964
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101001
System Description: Fedora 34 (Workstation Edition)

Configured using:
 'configure --prefix=/home/vonbrand'

Configured features:
ACL CAIRO DBUS FREETYPE GIF GLIB GMP GNUTLS GSETTINGS HARFBUZZ JPEG
LCMS2 LIBSELINUX LIBSYSTEMD LIBXML2 MODULES NOTIFY INOTIFY PDUMPER PNG
RSVG SECCOMP SOUND THREADS TIFF TOOLKIT_SCROLL_BARS X11 XDBE XIM XPM
GTK3 ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  value of $XMODIFIERS: @im=ibus
  locale-coding-system: utf-8-unix

Major mode: Fundamental

Minor modes in effect:
  tooltip-mode: t
  global-eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  buffer-read-only: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.


-- 
Dr. Horst H. von Brand                   User #22616 counter.li.org
Departamento de Informatica                    Fono: +56 32 2654431
Universidad Tecnica Federico Santa Maria             +56 32 2654239
Casilla 110-V, Valparaiso, Chile 2340000       Fax:  +56 32 2797513