Fix memory leak in QHostInfo

QHostInfo was leaking in the code path where it removes duplicate
name lookups after one has completed.

Task-number: QT-5121
Reviewed-by: Markus Goetz
(cherry picked from commit 73df7890923f377f19147466d9317fe1ec064b1d)

Change-Id: I26cc6a168ef8ea6cc18940300ca2eddd6777071d
Reviewed-on: http://codereview.qt.nokia.com/1363
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Markus Goetz

src/network/kernel/qhostinfo.cpp

@@ -527,6 +527,7 @@ void QHostInfoRunnable::run()
                 iterator.remove();
                 hostInfo.setLookupId(postponed->id);
                 postponed->resultEmitter.emitResultsReady(hostInfo);
+                delete postponed;
             }
         }
     }