Replace ldefs-boot with a much smaller file

Replace ldefs-boot with a much smaller file

 * Makefile.in (bootstrap-build,generate-ldefs-boot): New targets.
   (bootstrap): Depend on bootstrap-build.
 * admin/ldefs-clean.el: New file.
 * lisp/Makefile.in (compile-first): Depend on loaddefs.el
 * lisp/ldefs-boot.el: Remove.
 * lisp/ldefs-boot-auto.el: New file.
 * lisp/ldefs-boot-manual.el: New file.
 * lisp/loadup.el: Load ldefs-boot-manual.el.
 * src/emacs.c (generating_ldefs_boot): New variable.
   (main): Check whether we are generating ldefs.
 * src/eval.c (autoload-do-load): Dump autoload forms to stderr when
   requested.
 * src/lisp.h (generating_ldefs_boot): New variable.
 * admin/gitmerge.el, admin/make-tarball.txt, admin/notes/copyright,
   lisp/Makefile.in, lisp/cus-dep.el, lisp/emacs-lisp/elint.el,
   lisp/finder.el, lisp/loadup.el, msdos/mainmake.v2: Update reference to
   ldefs-boot.
 * admin/update_autogen: Alter mechanism for ldefs-boot generation.