automake: just use warnings, with no => FATAL.

automake: just use warnings, with no => FATAL.

Per Perl recommendation:
  https://perldoc.perl.org/warnings#Fatal-Warnings
Suggested by Collin Funk:
  https://lists.gnu.org/archive/html/automake/2025-01/msg00003.html
And in the Perl discussion:
  https://github.com/Perl/perl5/issues/22954#issuecomment-2622966302

* bin/aclocal.in: just use warnings, not making them fatal.
* bin/automake.in:
* contrib/tap-driver.pl:
* gen-testsuite-part:
* lib/Automake/ChannelDefs.pm:
* lib/Automake/Channels.pm:
* lib/Automake/Condition.pm:
* lib/Automake/Config.in:
* lib/Automake/Configure_ac.pm:
* lib/Automake/DisjConditions.pm:
* lib/Automake/FileUtils.pm:
* lib/Automake/General.pm:
* lib/Automake/Getopt.pm:
* lib/Automake/Item.pm:
* lib/Automake/ItemDef.pm:
* lib/Automake/Language.pm:
* lib/Automake/Location.pm:
* lib/Automake/Options.pm:
* lib/Automake/Rule.pm:
* lib/Automake/RuleDef.pm:
* lib/Automake/VarDef.pm:
* lib/Automake/Variable.pm:
* lib/Automake/Version.pm:
* lib/Automake/Wrap.pm:
* lib/Automake/XFile.pm:
* t/ax/deltree.pl:
* t/ax/extract-testsuite-summary.pl:
* t/check-fd-redirect.sh:
* t/tap-signal.tap:
* t/tests-environment-fd-redirect.sh:
* t/testsuite-summary-count-many.sh: