Fix bug in status_mail_report_add_cmd.php

Existing code was referencing the wrong variable ($a_graphs instead of $a_cmds), which caused the IF test to fail, which then caused duplicate entries to be created each time the "edit command" form was submitted.  This edit fixes the issue, tested on pfSense 2.1.5 nanobsd.

config/mailreport/status_mail_report_add_cmd.php

@@ -130,7 +130,7 @@
 			<input name="Submit" type="submit" class="formbtn" value="<?=gettext("Save");?>">
 			<a href="status_mail_report_edit.php?id=<?php echo $reportid;?>"><input name="cancel" type="button" class="formbtn" value="<?=gettext("Cancel");?>"></a>
 			<input name="reportid" type="hidden" value="<?=htmlspecialchars($reportid);?>">
-			<?php if (isset($id) && $a_graphs[$id]): ?>
+			<?php if (isset($id) && $a_cmds[$id]): ?>
 			<input name="id" type="hidden" value="<?=htmlspecialchars($id);?>">
 			<?php endif; ?>
 			</td>