ui-tree: specify parameter position for all htmlf formats

The GNU C library manual tells us that behavior is undefined if only
some formats has a specification for the parameter position.

Noticed-by: <mkraai@beckman.com>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>
diff --git a/ui-tree.c b/ui-tree.c
index 1cb09f7..ef44d61 100644
--- a/ui-tree.c
+++ b/ui-tree.c
@@ -43,7 +43,7 @@
 	while(idx < size) {
 		if (buf[idx] == '\n') {
 			buf[idx] = '\0';
-			htmlf("<tr><td class='no'><a name='%d'>%1$d</a></td><td class='txt'>",
+			htmlf("<tr><td class='no'><a name='%1$d'>%1$d</a></td><td class='txt'>",
 			      ++lineno);
 			html_txt(buf + start);
 			html("</td></tr>\n");