Keep `--silent-rules' across triggered automake reruns.

Keep `--silent-rules' across triggered automake reruns.

* automake.in (usage): Reformat to be a bit clearer.
(handle_configure): Remove substitutions %STRICTNESS% and
%USE-DEPS% in favor of a new substitution %AUTOMAKE-OPTIONS%
that carries over all needed flags.
* lib/am/configure.am (%MAKEFILE-IN%): Adjust rule.
* tests/flavor.test: New test, to ensure --$flavor (gnu,
gnits, foreign, cygnus), --ignore-deps, and --silent-rules are
preserved across automake reruns.
* tests/Makefile.am: Update.

Signed-off-by: Ralf Wildenhues <Ralf.Wildenhues@gmx.de>