Don't try to be smart with aclocal 1.8+ because (i) aclocal no

Don't try to be smart with aclocal 1.8+ because (i) aclocal no
longer updates aclocal.m4 if useless, (ii) if a file m4_included
by aclocal.m4 is changed it might require the importing of another
m4 extension file, i.e., aclocal must be run.
* bin/autoreconf.in (&run_aclocal, $aclocal_supports_force): New.
(&parse_args): Use --force with aclocal if required and supported.
(&autoreconf_current_directory): Use &run_aclocal.