Add ofs argument to cgit_log_link and use it in ui-log.c

This fixes a bug in the prev/next links on the log page: when on the default
branch the links to prev/next page would contain h=(null).

Signed-off-by: Lars Hjemli <hjemli@gmail.com>

ui-repolist.c

@@ -98,7 +98,7 @@ void cgit_print_repolist(struct cacheitem *item)
 			html_link_open(cgit_repourl(cgit_repo->url),
 				       NULL, "button");
 			html("summary</a>");
-			cgit_log_link("log", NULL, "button", NULL, NULL, NULL);
+			cgit_log_link("log", NULL, "button", NULL, NULL, NULL, 0);
 			cgit_tree_link("tree", NULL, "button", NULL, NULL, NULL);
 			html("</td>");
 		}