Restore overload mode accidentally disabled in a prior commit. Add a new

config option, LogOverloads, to log when a thread pool overload occurs.
This option defaults to "True" because the logging data is useful for
diagnosing threading issues.

bin/OpenSimDefaults.ini

@@ -292,6 +292,14 @@
     ; False items will be removed from the scene permanently
     UseTrashOnDelete = True
 
+    ; #
+    ; # Logging
+    ; #
+
+    ; Force logging when the thread pool approaches an overload condition
+    ; Provides useful data for post-mortem analysis even in a production
+    ; system with reduced logging
+    LogOverloads = True
 
 [Map]
     ;WorldMapModule = "WorldMap"