Update wizmainwindow.h

错误输出：
[ 72%] Building CXX object src/CMakeFiles/wiznote.dir/wizmainwindow.cpp.o                                                                            
/home/usr/software/WizQTClient/src/wizmainwindow.cpp: In member function ‘void Core::Internal::MainWindow::cleanOnQuit()’:
/home/usr/software/WizQTClient/src/wizmainwindow.cpp:198:20: error: ‘sleep’ was not declared in this scope
             sleep(1);
                    ^
make[2]: *** [src/CMakeFiles/wiznote.dir/wizmainwindow.cpp.o] 错误 1
make[1]: *** [src/CMakeFiles/wiznote.dir/all] 错误 2
make: *** [all] 错误 2