Issue #12545: Remove deprecated <u> tag from account_sponsorship_page

The old HTML <u> tag is deprecated and has no direct replacement. We
should be using CSS for styling instead.

account_sponsor_page.php

@@ -285,7 +285,7 @@
 		echo '<td><a href="' . string_get_bug_view_url( $row['bug'] ) . '">' . bug_format_id( $row['bug'] ) . '</a></td>';
 		echo '<td>' . project_get_field( $t_bug->project_id, 'name' ) . '&#160;</td>';
 		echo '<td class="right">' . $t_released_label . '&#160;</td>';
-		echo '<td><a title="' . $t_resolution . '"><u>' . $t_status . '</u>&#160;</a></td>';
+		echo '<td><a title="' . $t_resolution . '"><span class="underline">' . $t_status . '</span>&#160;</a></td>';
 
 		# summary
 		echo '<td>' . string_display_line( $t_bug->summary );