do { $configure_name||=$_ if -f $_ } for ("configure.ac");
$configure_name or confess "Cannot find configure.{in,ac}";
my $configure_in=_readfile($configure_name);
do { $configure_name||=$_ if -f $_ } for ("configure.ac");
$configure_name or confess "Cannot find configure.{in,ac}";
my $configure_in=_readfile($configure_name);