PollTimer should be stop and destroyed when QApplication closing

When QApplication closing, sometime happen crash

PC: /usr/lib/libQt5Network.so.5(_ZN35QNetworkConfigurationManagerPrivate11pollEnginesEv+0x67) [0xb4e01edc]
LR: /usr/lib/libQt5Network.so.5(_ZN35QNetworkConfigurationManagerPrivate11pollEnginesEv+0x24) [0xb4e01e99]

Backtrace:
/usr/lib/libQt5Network.so.5(_ZN35QNetworkConfigurationManagerPrivate11pollEnginesEv+0x67) [0xb4e01edc]
/usr/lib/libQt5Network.so.5(+0xafcb9) [0xb4e45cb9]
/usr/lib/libQt5Core.so.5(_ZN11QMetaObject8activateEP7QObjectiiPPv+0x4c0) [0xb52d5291]
/usr/lib/libQt5Core.so.5(_ZN6QTimer10timerEventEP11QTimerEvent+0x1e) [0xb52dd077]
/usr/lib/libQt5Core.so.5(_ZN7QObject5eventEP6QEvent+0xc2) [0xb52d5c47]
/usr/lib/libQt5Widgets.so.5(_ZN19QApplicationPrivate13notify_helperEP7QObjectP6QEvent+0x50) [0xb552f911]
/usr/lib/libQt5Widgets.so.5(_ZN12QApplication6notifyEP7QObjectP6QEvent+0x66c) [0xb5533359]
/usr/lib/libQt5Core.so.5(_ZN16QCoreApplication14notifyInternalEP7QObjectP6QEvent+0x42) [0xb52b9c43]
/usr/lib/libQt5Core.so.5(_ZN14QTimerInfoList14activateTimersEv+0x3de) [0xb52ee23f]
/usr/lib/libQt5Core.so.5(+0x1c758f) [0xb52ee58f]
/usr/lib/libglib-2.0.so.0(g_main_context_dispatch+0x168) [0xb2ea9aac]
/usr/lib/libglib-2.0.so.0(+0x41d8c) [0xb2ea9d8c]
/usr/lib/libglib-2.0.so.0(g_main_context_iteration+0x34) [0xb2ea9e28]
/usr/lib/libQt5Core.so.5(_ZN20QEventDispatcherGlib13processEventsE6QFlagsIN10QEventLoop17ProcessEventsFlagEE+0x44) [0xb52ee78d]
/usr/lib/libQt5Core.so.5(_ZN10QEventLoop13processEventsE6QFlagsINS_17ProcessEventsFlagEE+0x10) [0xb52b8c85]
/usr/lib/libQt5Core.so.5(_ZN10QEventLoop4execE6QFlagsINS_17ProcessEventsFlagEE+0xe0) [0xb52b8f35]
/usr/lib/libQt5Core.so.5(_ZN7QThread4execEv+0x58) [0xb51930cd]
/usr/lib/libQt5Core.so.5(+0x6ebcb) [0xb5195bcb]
/lib/libpthread.so.0(+0x6e64) [0xb4abee64]
/lib/libc.so.6(+0xcccf0) [0xb4fe7cf0]