avoid creating the Bonjour Controller singleton unnecessarily

macosx/BonjourController.h

@@ -30,6 +30,7 @@
 }
 
 + (BonjourController *) defaultController;
++ (BOOL) defaultControllerExists;
 
 - (void) startWithPort: (int) port;
 - (void) stop;

macosx/BonjourController.m

@@ -39,6 +39,11 @@ BonjourController * fDefaultController = nil;
     return fDefaultController;
 }
 
++ (BOOL) defaultControllerExists
+{
+    return fDefaultController != nil;
+}
+
 - (void) dealloc
 {
     [fService release];

macosx/Controller.m

@@ -671,6 +671,7 @@ static void sleepCallback(void * controller, io_service_t y, natural_t messageTy
     fQuitting = YES;
     
     //stop the Bonjour service
+    if ([BonjourController defaultControllerExists])
         [[BonjourController defaultController] stop];
 
     //stop blocklist download
@@ -1472,7 +1473,6 @@ static void sleepCallback(void * controller, io_service_t y, natural_t messageTy
                             [torrent closeRemoveTorrent: deleteData];
                     }];
                     
-
                     [fTableView beginUpdates];
                     beganUpdate = YES;
                 }

macosx/PrefsController.m

@@ -1050,7 +1050,10 @@
     if ([fDefaults boolForKey:@"RPC"] && [fDefaults boolForKey: @"RPCWebDiscovery"])
         [[BonjourController defaultController] startWithPort: [fDefaults integerForKey: @"RPCPort"]];
     else
+    {
+        if ([BonjourController defaultControllerExists])
             [[BonjourController defaultController] stop];
+    }
 }
 
 - (void) updateRPCWhitelist