Remove libxcbsync0

ci/travis/before_install.sh

@@ -12,7 +12,7 @@ elif [ $TRAVIS_OS_NAME == "linux" ]
 then
     sudo apt-get update
     sudo apt-get install libxcb1 libxcb1-dev libx11-xcb1 libx11-xcb-dev libxcb-keysyms1 libxcb-keysyms1-dev libxcb-image0 \
-            libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm4 libxcb-icccm4-dev libxcb-sync0 libxcb-sync0-dev \
+            libxcb-image0-dev libxcb-shm0 libxcb-shm0-dev libxcb-icccm4 libxcb-icccm4-dev \
             libxcb-xfixes0-dev libxrender-dev libxcb-shape0-dev libxcb-randr0-dev libxcb-render-util0 \
             libxcb-render-util0-dev libxcb-glx0-dev libgl1-mesa-dri libegl1-mesa libpcre3-dev \
             curl qt5-qmake qtbase5-dev qttools5-dev-tools libqt5svg5-dev libdbus-1-dev libdbus-glib-1-dev autoconf automake libtool