avoid using pagespec_match_list here

I forgot to check if it was called from preprocess, and it is
not; it's called by a format hook. If an error is thrown from
a format hook, wiki build fails, so we don't want that.

IkiWiki/Plugin/linkmap.pm

@@ -56,10 +56,11 @@ sub genmap ($) {
 
 	# Get all the items to map.
 	my %mapitems = ();
-	foreach my $item (pagespec_match_list([keys %links],
-				$params{pages}, location => $params{page})) {
+	foreach my $item (keys %links) {
+		if (pagespec_match($item, $params{pages}, location => $params{page})) {
 			$mapitems{$item}=urlto($item, $params{destpage});
 		}
+	}
 
 	my $dest=$params{page}."/linkmap.png";