Speed generation of ldefs-boot-auto

Speed generation of ldefs-boot-auto

Previously, generation of ldefs-boot-auto required at least one full
bootstrap and, in extreme cases, two. Now, from build system, it
requires the same time as taken to dump Emacs.

* Makefile.in: Remove all calls, pass to src.
* admin/ldefs-clean.el: Update for changed messages.
* lisp/Makefile.in (compile-first-delete): Add.
* lisp/ldefs-boot-auto.el: Update.
* src/Makefile.in (generate-ldefs-boot): Add.