ui-shared: add now-dynamic age to footer

Now ages advance at the client, we can add one
to the generated footer.

Signed-off-by: Andy Green <andy@warmcat.com>
diff --git a/ui-shared.c b/ui-shared.c
index 2d79e36..6d19c58 100644
--- a/ui-shared.c
+++ b/ui-shared.c
@@ -849,7 +849,9 @@
 		htmlf("<div class='footer'>generated by <a href='https://git.zx2c4.com/cgit/about/'>cgit %s</a> "
 			"(<a href='https://git-scm.com/'>git %s</a>) at ", cgit_version, git_version_string);
 		html_txt(show_date(time(NULL), 0, cgit_date_mode(DATE_ISO8601)));
-		html("</div>\n");
+		html(" (");
+		cgit_print_age(time(NULL), 0, -1);
+		html(" ago)</div>\n");
 	}
 	html("</div> <!-- id=cgit -->\n");
 	html("</body>\n</html>\n");