* aclocal.in: Use Automake::FileUtils.

* aclocal.in: Use Automake::FileUtils.
(parse_arguments, scan_configure, scan_m4_files): Never call
"die" to print an error message.  Use print and exit.
* automake.in: Use Automake::FileUtils.
* lib/Automake/General.pm ($debug, $help, $tmp, $verbose,
$version, &debug, &getopt, &mktmpdir, &verbose): Remove.
(END): Do not massage Perl's exit code.  Do not clean any temporary
directory.
(find_file, mtime, update_file, xsystem, contents): Move to ...
* lib/Automake/FileUtils.pm: ... this new file.  Adjust to
report errors using Channels.
(handle_exec_errors, xqx): New functions, from Autoconf.
* lib/Automake/Makefile.am (dist_perllib_DATA): Add FileUtils.pm.