xsyncbasedpoller ctor initialize m_sync_event
Fix PVS-Studio issue "src/plugins/xsync/xsyncbasedpoller.cpp:63: warning: V1077 The 'XSyncBasedPoller' constructor contains potentially uninitialized members. Inspect the following: m_sync_event.".
Fix PVS-Studio issue "src/plugins/xsync/xsyncbasedpoller.cpp:63: warning: V1077 The 'XSyncBasedPoller' constructor contains potentially uninitialized members. Inspect the following: m_sync_event.".