Add the migration for friends and guard the presence Report function

OpenSim/Data/MySQL/MySQLPresenceData.cs

@@ -75,6 +75,10 @@ namespace OpenSim.Data.MySQL
         public bool ReportAgent(UUID sessionID, UUID regionID, string position,
                 string lookAt)
         {
+            PresenceData[] pd = Get("SessionID", sessionID.ToString());
+            if (pd.Length == 0)
+                return false;
+
             MySqlCommand cmd = new MySqlCommand();
 
             cmd.CommandText = String.Format("update {0} set RegionID=?RegionID, Position=?Position, LookAt=?LookAt', Online='true' where `SessionID`=?SessionID", m_Realm);

OpenSim/Data/MySQL/Resources/001_Friends.sql

@@ -0,0 +1,9 @@
+BEGIN;
+
+CREATE TABLE `Friends` (
+    `PrincipalID` CHAR(36) NOT NULL,
+    `FriendID` VARCHAR(255) NOT NULL,
+    `Flags` CHAR(16) NOT NULL DEFAULT '0'
+) ENGINE=InnoDB;
+
+COMMIT;