Let Automake support `configure.ac'. * automake.in: In the comments, prefer `configure.ac' to `configure.in'. When using &am_conf_error, don't repeat `in configure.in', since the function already reports it. When referring to `configure.in' use `$configure_ac' instead. (configure_ac): New global variable. (scan_configure, scan_one_configure_file): Rename as... (scan_autoconf_files, scan_one_autoconf_file): this. (scan_autoconf_files): Compute $configure_ac. (transform): New function. (handle_configure): Use it to transform CONFIGURE_AC in `remake.am' and in `remake-hdr.am'. (common_files): Also consider `configure.ac'. Use consistently single quotes. * aclocal.in (configure_ac): New variable. Use it. * texi-vers.am: Depend on CONFIGURE_AC not configure.in. * remake.am: Likewise. * remake-hdr.am: Likewise.