perlapi: Tabularize display of config.h symbols

Certain symbols in config.h have been displayed with no addtional
information.  The lack of information is because the symbol's name says
it all. For example HAS_SETENV is a boolean indicating if setenv() is
available on the platform.  No further explanation is needed than the
introductory paragraph at the beginning of the section.

Prior to this commit, these symbols were displayed as a comma separated
list wrapping across multiple lines.

This commit organizes them into a table with columns, making them much
easier to read.

Author: khwilliamson

autodoc.pl

@@ -2868,13 +2868,7 @@ ($destpod)
 
 
 foreach my $name (keys %list_only) {
-    my @this_list = $list_only{$name}{list}->@*;
-    my $text = "";
-    foreach my $entry (sort dictionary_order @this_list) {
-        $text .= ",S< > " if $text; # The S< > makes things less densely
-                                    # packed, hence more readable
-        $text .= "C<$entry>";
-    }
+    my $text = make_verbatim_list($list_only{$name}{list}->@*);
     $valid_sections{$genconfig_scn}{footer}
                                     =~ s/$list_only{$name}{placement}/$text/;
 }