* lib/Autom4te/General.pm: Use `carp' and `croak', not `warn' and

* lib/Autom4te/General.pm: Use `carp' and `croak', not `warn' and
`die'.
(&END): New.
* bin/autoconf.in, bin/autom4te.in, bin/autoupdate.in: Remove your
`END', as `Autom4te::General::END' will be triggered.
* bin/autoupdate.in, bin/autoscan.in: Improve error messages accuracy.
* bin/autoupdate.in (File::Compare, File::Copy): Use them instead of
system to run `mv', `rm', and `cmp'.