macOS/iOS: Workaround an Apple bug which could result in a race-condition when accessing a WebInputStream from multiple threads

modules/juce_core/native/juce_mac_Network.mm

@@ -449,6 +449,9 @@ struct BackgroundDownloadTask  : public URL::DownloadTask
         if (session != nullptr)
             downloadTask = [session downloadTaskWithRequest:request];
 
+        // Workaround for an Apple bug. See https://github.com/AFNetworking/AFNetworking/issues/2334
+        [request HTTPBody];
+
         [request release];
     }
 
@@ -1118,6 +1121,9 @@ private:
                     [req addValue: juceStringToNS (value) forHTTPHeaderField: juceStringToNS (key)];
             }
 
+            // Workaround for an Apple bug. See https://github.com/AFNetworking/AFNetworking/issues/2334
+            [req HTTPBody];
+
             connection.reset (new URLConnectionState (req, numRedirectsToFollow));
         }
     }