* lib/autoconf/autoconf.m4: Include it.
* lib/autoconf/functions.m4: Use AN_FUNCTION for all the functions
that were listed in the original autoscan.list.
* lib/autoconf/headers.m4: Similarly with headers.
* lib/freeze.mk (autoconf_m4f_dependencies): Add autoscan.m4.
(.m4.m4f): Don't pass --prepend-include, since that's done by
tests/autom4te itself.
* lib/autoscan/Makefile.am: Include freeze.mk.
(autoscan.list): New target --this file is no longer a source.
(autoscan.pre): New file.
Adjust all uses.
(&init_tables): When --debug, report the list of rules to ease
tracking changes in autoscan.list.
* lib/autoscan/autoscan.list (function): Strip comments, sort.