[ticket/9757] Fix empty template variable {HISTORY_TITLE}

The template variable {HISTORY_TITLE} was always being set to the empty string.
It is now filled with the title of the currently displayed message.  It is not
showed in prosilver or subsilver2 for aesthetic reasons (title is already
prominent)

PHPBB3-9757

phpBB/includes/functions_privmsgs.php

@@ -1751,6 +1751,8 @@ function message_history($msg_id, $user_id, $message_row, $folder, $in_post_mode
 		return false;
 	}
 
+	$title = $row['message_subject'];
+
 	$rowset = array();
 	$bbcode_bitfield = '';
 	$folder_url = append_sid("{$phpbb_root_path}ucp.$phpEx", 'i=pm') . '&folder=';
@@ -1774,8 +1776,6 @@ function message_history($msg_id, $user_id, $message_row, $folder, $in_post_mode
 	while ($row = $db->sql_fetchrow($result));
 	$db->sql_freeresult($result);
 
-	$title = $row['message_subject'];
-
 	if (sizeof($rowset) == 1 && !$in_post_mode)
 	{
 		return false;

phpBB/styles/prosilver/template/ucp_pm_history.html

@@ -1,7 +1,7 @@
 
 <h3 id="review">
 	<span class="right-box"><a href="#review" onclick="viewableArea(getElementById('topicreview'), true); var rev_text = getElementById('review').getElementsByTagName('a').item(0).firstChild; if (rev_text.data == '{LA_EXPAND_VIEW}'){rev_text.data = '{LA_COLLAPSE_VIEW}'; } else if (rev_text.data == '{LA_COLLAPSE_VIEW}'){rev_text.data = '{LA_EXPAND_VIEW}'};">{L_EXPAND_VIEW}</a></span>
-	{L_MESSAGE_HISTORY}: {HISTORY_TITLE}
+	{L_MESSAGE_HISTORY}:
 </h3>
 
 <div id="topicreview">

phpBB/styles/subsilver2/template/ucp_pm_history.html

@@ -6,7 +6,7 @@
 
 <table class="tablebg" width="100%" cellspacing="1">
 <tr>
-	<th align="center">{L_MESSAGE_HISTORY} - {HISTORY_TITLE}</th>
+	<th align="center">{L_MESSAGE_HISTORY}</th>
 </tr>
 <tr>
 	<td class="row1"><div style="overflow: auto; width: 100%; height: 300px;">