Fix HypergridLinker.Check4096()

Make the optimization with IEnumerable.Except() in Check4096 actually work by providing an appropriate equality definition for GridRegion objects.

OpenSim/Services/Interfaces/IGridService.cs

@@ -97,7 +97,7 @@ namespace OpenSim.Services.Interfaces
         int GetRegionFlags(UUID scopeID, UUID regionID);
     }
 
-    public class GridRegion
+    public class GridRegion : Object
     {
 
         /// <summary>
@@ -225,6 +225,33 @@ namespace OpenSim.Services.Interfaces
             EstateOwner = ConvertFrom.EstateOwner;
         }
 
+        # region Definition of equality
+
+        /// <summary>
+        /// Define equality as two regions having the same, non-zero UUID.
+        /// </summary>
+        public bool Equals(GridRegion region)
+        {
+            if ((object)region == null)
+                return false;
+            // Return true if the non-zero UUIDs are equal:
+            return (RegionID != UUID.Zero) && RegionID.Equals(region.RegionID);
+        }
+
+        public override bool Equals(Object obj)
+        {
+            if (obj == null)
+                return false;
+            return Equals(obj as GridRegion);
+        }
+
+        public override int GetHashCode()
+        {
+            return RegionID.GetHashCode() ^ TerrainImage.GetHashCode();
+        }
+
+        #endregion
+
         /// <value>
         /// This accessor can throw all the exceptions that Dns.GetHostAddresses can throw.
         ///