(&init_tables): Die when a word which is already handled by
explicit macros is mapped to the default macro.
(&print_unique): Remove, inlined in...
(&output_kind): here.
(File::Basename): Use it.
(&output): Sort the CONFIG_FILES.
* acheaders: Normalize.
* acfunctions: Likewise.
(&init_tables): Use them.
* acheaders: Run `autoconf -t AC_CHECK_HEADERS:'$1'' on the fileutils,
and include all these headers in here.
Don't specify `AC_CHECK_HEADERS' as it's the default.